Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “evolutionary conservation”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 559 records · Page 31Linked to original sources
PubMed1999

Identification and expression of a novel family of bHLH cDNAs related to Drosophila hairy and enhancer of split.

In this report we describe the initial characterization of murine, human, and Drosophila hesr-1 (for hairy and enhancer of split related-1) a novel evolutionary conserved family of hairy/enhancer of split homologs. Hesr-1 cDNAs display features typical of hairy and enhancer of split-type bHLH proteins including a N-terminal bHLH domain a conserved orange domain immediately C-terminal to the bHLH region. Despite their similarity to known hairy/enhancer of split homologs, hesr-1 cDNAs are divergent members of the hairy and enhancer of split bHLH family since the degree of sequence identity within the bHLH and their nearest homologs are relatively low. Moreover, the tetrapeptide motif, WRPW, which is found in all hairy and enhancer of split family members, is not present in hesr-1. Rather, a variant of this motif, YRPW, is found. Analysis of embryonic murine hesr-1 expression by in situ hybridization reveals strong expression in the somitic mesoderm, the central nervous system, the kidney, the heart, nasal epithelium, and limbs indicating a role for hesr-1 in the development of these tissues. Like the enhancer of split cDNAs in Drosophila, we show that hesr-1 expression depends critically on signaling through the notch pathway in murine embryos, suggesting that aspects of hesr-1 regulation and function might also be evolutionary conserved.

Amino Acid Sequence↗
PubMed2004

Expression of two protein isoforms of PAX7 is controlled by competing cleavage-polyadenylation and splicing.

The PAX7 gene encodes an evolutionary conserved transcription factor that is involved in the determination of the myogenic cell lineage during the development of vertebrates. In the postnatal period, the function of PAX7 is ultimately required for the specification of muscle satellite cells. The fact that PAX7 is expressed in fast proliferating embryonal myoblasts and in quiescent satellite cells of adults raised the question whether different PAX7 protein isoforms may have distinct roles in these myogenic precursors. Previously, we identified a human PAX7 mRNA encoding a C-terminus which did not show any sequence similarity to the PAX7 proteins of other organisms. So far, there was no further information available concerning the biological nature and significance of this form of PAX7. Here, we show that expression of PAX7 can be regulated by differential transcriptional termination either in exon 9 or in exon 8. Thereby, differential mRNA cleavage-polyadenylation and splicing of PAX7 may result in production of two alternative protein forms that contain or exclude the evolutionary conserved carboxy-terminal domain, respectively. The existence of both protein isoforms in vivo was confirmed by Western blot analysis. These data imply that the alternative C-termini of PAX7 may convey different functions to the corresponding protein isoforms.

Alternative Splicing↗
PubMed1995

Bcl-2 and Bcl-2-related proteins in apoptosis regulation.

In this review we have discussed the importance of Bcl-2 and related proteins in the regulation of apoptotic cell death in mammalian systems. It is clear that Bcl-2 plays a critical role in controlling many forms of PCD. Bcl-2 seems to have particular significance in lymphocyte development and the function of the immune system. We have also discussed the increasing size of the newly identified Bcl-2 family. There are a number of Bcl-2 homologues in human, murine, avian, nematode, and viral systems. The evolutionary conservation of the function of the Bcl-2 homologues, reinforces the importance of PCD in all complex organisms. Some of these bcl-2-like genes function as agonists and others as antagonists. Despite the seemingly universal importance of Bcl-2, it is unable to prevent PCD in all systems. In addition, we have described a role for other Bcl-2 family members in systems in which Bcl-2 is ineffective and supplied a potential rationale for the large number of genes involved in the regulation of PCD. Identification and functional analysis of the Bcl-2 family members reveals the complex nature of cell death regulation. As we begin to appreciate the significance of PCD in the control of development and homeostasis, its regulation at the molecular level is becoming better understood. Bcl-2 has long been the only known intracellular regulator of the PCD pathway(s), although its ability to prevent apoptosis is not universal. We now know that bcl-2 is only one member of an evolutionary conserved family of genes which display different patterns of expression as well as function. At least two family members, Bcl-xs and Bax, act in opposition to Bcl-2. The discovery of these new family members, including those with Bcl-2-like function and antagonists, should help clear up the discrepancies seen in Bcl-2's ability to protect cells from PCD. In doing so, we will be able to further define the pathways associated with cell death signaling. The study of these family members, as well as the non-related genes of the PCD pathways (ced-3, ced-4, ice) should lead us to understanding of how cells of multicellular organisms make decisions to die.

Animals↗
PubMed2004

Mutational-reporter transgenes rescued from mice lacking either Mgmt, or both Mgmt and Msh6 suggest that O6-alkylguanine-induced miscoding does not contribute to the spontaneous mutational spectrum.

O6-methylguanine methyltransferase, Mgmt, constitutes the first line of defense against O6-alkylguanine, which can result in G : C to A : T transitions upon DNA replication. Mgmt has been found in organisms as diverse as archaebacteria and mammals. This evolutionary conservation suggests that all organisms may be exposed to either endogenous or environmental alkylating agents. We thus hypothesized that tissues of Mgmt-/- mice would exhibit elevated mutant frequencies. Employing the Big Blue trade mark transgenic system, we evaluated lacI mutants rescued from liver and small intestinal DNA of young Mgmt-/- mice. Interestingly, while there was a small difference between Mgmt-/- mice and controls with respect to lacI mutant frequency, no differences attributable to Mgmt deficiency were apparent in the mutational spectra. Although mutations stemming from O6-guanine alkylations would be predicted to be cumulative, we found no evidence of an Mgmt-dependent alteration in mutation spectrum in DNA samples from 12 month-old mice. To optimize our ability to detect mutations resulting from O6-alkylguanine-induced G : T mismatches, mice with combined deficiencies of Mgmt and the DNA mismatch repair molecule, Msh6, were analysed. In spite of this strategy, we observed no significant differences between Mgmt-/- Msh6-/- and Msh6-/- mouse lacI mutations, except for a trend towards a greater percentage (of total transitions) of G : C to A : T changes in Mgmt-/-Msh6-/- livers. Therefore, despite the striking evolutionary conservation of Mgmt, deficiency of this gene did not significantly impact the spontaneous lacI mutational spectrum in vivo.

Age Factors↗
PubMed2026

Single-organ proteomics in Drosophila melanogaster larva.

The combination of genetic accessibility, organ complexity, evolutionary conservation, and cost-efficiency makes Drosophila melanogaster (Dm) a well-known model system for biomedical and fundamental biological research. Proteomic analysis of single organs enables the identification and quantification of proteins expressed in specific organs. This will help to uncover specific biological functions and unique protein profiles that are not detectable in whole-organism analyses. In this study we have isolated single organs form Dm larvae, and we have performed a deep proteomics mapping by following a minimal manipulation preparation procedure. The combined dataset across all organs comprised 9132 identified proteins. As anticipated, principal component analysis (PCA) revealed clear separation between the proteomes of most organs, confirming distinct protein profiles. These findings demonstrate the applicability of the sample preparation strategy for high-resolution proteomic characterization of individual organs in Drosophila. Given the extensive genetic tools available for this model organism, our approach has the potential to open new avenues for proteomic studies in Drosophila melanogaster and any other biological systems where the sample amount is limiting. SIGNIFICANCE STATEMENT: Drosophila melanogaster is a well-known model system for biomedical and fundamental biological research that serves as a valuable in vivo model organism due to its high degree of evolutionary conservation with higher vertebrates, tractable genetics, and logistical efficiency. However, the proteome of Drosophila at single organ level has been elusive to date, due to several factors like low sensitivity of previous generation mass spectrometers and sample preparation procedures, difficult isolation of some organs. In this study we have applied a compilation of advanced methods including minimal sample manipulation together with simple, straightforward and efficient protein extraction and digestion methods. Obtained peptides were minimally handled to be analyzed by applying specific and sensitive nLC methods coupled on-line to state-of-the-art MS/MS system. Altogether, the applied strategy allowed us to get the first single organ study to date for this animal. These datasets represent a significative resource for future genomic, transcriptomic and proteomic studies in Drosophila, as multi-omic integration requires deep proteomics to translate data into functional biochemistry, and serves as a critical bridge and an indispensable standalone resource across the genomic, transcriptomic, and proteomic landscapes.

Animals↗
PubMed2006

Site-specific glycosylation analysis of the bovine lysosomal alpha-mannosidase.

Lysosomal alpha-mannosidase is a broad specificity exoglycosidase involved in the ordered degradation of glycoproteins. The bovine enzyme is used as an important model for understanding the inborn lysosomal storage disorder alpha-mannosidosis. This enzyme of about 1,000 amino acids consists of five peptide chains, namely a- to e-peptides and contains eight N-glycosylation sites. The N(497) glycosylation site of the c-peptide chain is evolutionary conserved among LAMANs and is very important for the maintenance of the lysosomal stability of the enzyme. In this work, relying on an approach based on mass spectrometric techniques in combination with exoglycosidase digestions and chemical derivatizations, we will report the detailed structures of the N-glycans and their distribution within six of the eight N-glycosylation sites of the bovine glycoprotein. The analysis of the PNGase F-released glycans from the bovine LAMAN revealed that the major structures fall into three classes, namely high-mannose-type (Fuc(0-1)Glc(0-1)Man(4-9)GlcNAc(2)), hybrid-type (Gal(0-1)Man(4-5)GlcNAc(4)), and complex-type (Fuc(0-1)Gal(0-2)Man(3)GlcNAc(3-5)) N-glycans, with core fucosylation and bisecting GlcNAc. To investigate the exact structure of the N-glycans at each glycosylation site, the peptide chains of the bovine LAMAN were separated using SDS-PAGE and in-gel deglycosylation. These experiments revealed that the N(497) and N(930) sites, from the c- and e-peptides, contain only high-mannose-type glycans Glc(0-1)Man(5-9)GlcNAc(2), including the evolutionary conserved Glc(1)Man(9)GlcNAc(2) glycan, and Fuc(0-1)Man(3-5)GlcNAc(2), respectively. Therefore, to determine the microheterogeneity within the remaining glycosylation sites, the glycoprotein was reduced, carboxymethylated, and digested with trypsin. The tryptic fragments were then subjected to concanavalin A (Con A) affinity chromatography, and the material bound by Con A-Sepharose was purified using reverse-phase high-performance liquid chromatography (HPLC). The tandem mass spectrometry (ESI-MS/MS) and the MALDI analysis of the PNGase F-digested glycopeptides indicated that (1) N(692) and N(766) sites from the d-peptide chain both bear glycans consisting of high-mannose (Fuc(0-1)Man(3-7)GlcNAc(2)), hybrid (Fuc(0-1) Gal(0-1)Man(4-5)GlcNAc(4)), and complex (Fuc(0-1)Gal(0-2)Man(3)GlcNAc(4-5)) structures; and (2) the N(367) site, from the b-peptide chain, is glycosylated only with high-mannose structures (Fuc(0-1)Man(3-5)GlcNAc(2)). Taking into consideration the data obtained from the analysis of either the in-gel-released glycans from the abc- and c-peptides or the tryptic glycopeptide containing the N(367) site, the N(133) site, from the a-peptide, was shown to be glycosylated with truncated and high-mannose-type (Fuc(0-1)Man(4-5)GlcNAc(2)), complex-type (Fuc(0-1)Gal(0-1)Man(3)GlcNAc(5)), and hybrid-type (Fuc(0-1)Gal(0-1)Man(5)GlcNAc(4)) glycans.

Amino Acid Sequence↗
PubMed1996

CAM-FGF receptor interactions: a model for axonal growth.

A number of experimental paradigms have been used to demonstrate that NCAM, N-cadherin, and L1 stimulate axonal growth. The molecular basis of this response has been extensively studied and a range of agents that inhibit neurite outgrowth stimulated by the above CAMs, but not integrins, have now been identified. These studies pointed to the activation of a tyrosine kinase-PLCgamma cascade as being important for the neurite outgrowth responses stimulated by all three CAMs, and this was substantiated by the identification of agents that could activate the cascade and mimic the growth response. In this review we will suggest that the neurite growth response stimulated by these CAMs is mediated by activation of the fibroblast growth factor receptor (FGFR) in neurons and that this results in the recruitment and activation of PLCgamma via interactions of its SH2 domain with the activated receptor. In this context the key events downstream from activation of PLCgamma required for neurite growth appear to be the conversion of diacylglycerol (DAG) to arachidonic acid (AA) via DAG lipase activity, followed by an increased influx of calcium into the neurons. The evolutionary conservation of putative binding motifs between the above CAMs and the FGFR suggests that activation of the FGFR-PLCgamma cascade by the CAMs might involve a direct CAM-FGFR interaction. The identification of the binding motifs also allows for predictions to be made concerning whether other CAMs might directly interact with the FGFR.

Amino Acid Sequence↗
PubMed2001

Identification and characterization of human BIC, a gene on chromosome 21 that encodes a noncoding RNA.

BIC was originally identified as a gene transcriptionally activated by promoter insertion at a common retroviral integration site in B cell lymphomas induced by avian leukosis virus (Tam et al., Mol. Cell. Biol. 17 (1997) 1490). The human homolog of this gene was cloned and characterized. It consists of three exons within a 13 kb region located in chromosome 21q21. Similar to the avian homolog, the human BIC lacks a long open reading frame (ORF). Highest levels of BIC expression are detected in the spleen and thymus by Northern analysis. In addition, the mouse homolog of BIC was identified. Comparison of BIC cDNAs from human, mouse and chicken reveals 78% identity over 138 nucleotides. However, there is no homology among the multiple short ORFs present in these cDNAs. The region of sequence homology is predicted by computer analysis to form an imperfect RNA duplex, which is structurally similar among the three species. Based on the lack of a conserved ORF and the evolutionary conservation of RNA secondary structure, we presume that BIC functions as a noncoding RNA.

Animals↗
PubMed2002

Three novel human VMD2-like genes are members of the evolutionary highly conserved RFP-TM family.

The RFP-TM protein family was first described in Caenorhabditis elegans as hypothetical transmembrane proteins containing a conserved 350-400 amino acid domain including the invariant peptide motif RFP. The VMD2 gene underlying Best disease was shown to represent the first human member of the RFP-TM protein family. More than 97% of the disease-causing mutations are located in the N-terminal RFP-TM domain implying important functional properties. Here, we have identified three novel VMD2-related human genes (VMD2L1, VMD2L2 and VMD2L3) demonstrating a high degree of conservation in their respective RFP-TM domains. Each of the VMD2-like proteins has a unique C-terminus that lack similarity to other proteins or motifs. By FISH analysis, VMD2L1 was localised to chromosome 19p13.2-p13.12, VMD2L2 to 1p32.3-p33 and VMD2L3 to 12q14.2-q15. RT-PCR analyses revealed tissue-restricted expression of the three genes with both VMD2L1 and VMD2L2 abundantly transcribed in colon. VMD2L1 is present in the retinal pigment epithelium while VMD2L3 shows predominant expression in skeletal muscle.

Amino Acid Sequence↗
PubMed2002

Phylogenetic analysis of Hoxa 11 sequences reveals absence of transposable elements, conservation of transcription factor binding sites, and suggests antisense coding function.

Nine thousand and eighty-eight base pairs of the chicken Hoxa 11 gene, including 8470 bases 5' of the translation start site were sequenced, and the characteristics of the upstream sequence investigated. Consistent with previous findings that middle repetitive elements are rare in the HoxA cluster, no repetitive elements were found other than simple oligonucleotide repeats. Multiple and pairwise alignments of the chicken upstream sequence with its human and mouse orthologs revealed multiple regions of 80% or higher homology across species. For the chicken, these regions were separated by sequences with no significant homology to human, mouse, or in most cases any other Genbank sequences. Selective clustering of transcription factor binding motifs was found to occur within the conserved homologous regions, suggesting evolutionary conservation of critical regulatory sequences. Of particular interest, seven conserved Cdx binding sites were found in the Hoxa 11 promoter, suggesting regulation by a non-clustered Caudal homeobox gene. Previous analysis of the mouse and human Hoxa 11 genes found a conserved antisense transcript, of unknown function. The chicken Hoxa 11 antisense strand included a conserved open reading frame capable of encoding 168 amino acids. Comparison of this region in mouse and chicken showed seven insertion/deletions, with each a multiple of three bases, thereby preserving open reading frame.

Animals↗
PubMed2000

Phylogenetic analysis and experimental approaches to study color vision in vertebrates.

To elucidate the molecular mechanisms of vertebrate color vision, it is essential to establish associations between amino acid substitutions and the directions of lambda max shifts of visual pigments. In this way, we can identify critical amino acid changes that may be responsible for lambda max shifts of visual pigments. In this process, we may consider only highly conserved residues, simply because the evolutionary conservation often implies functional importance. Using such an "evolutionary model" as a convenient tool in designing mutagenesis experiments, we can test specific hypotheses on the molecular mechanisms that are responsible for color vision in vertebrates. Virtually any vertebrate opsin cDNA can be expressed in COS cells, reconstituted with 11-cis-retinal, and the lambda max values of the regenerated pigments can be measured rather easily. By constructing mutant pigments with desired amino acid changes and conducting the in vitro assay and comparing their lambda max values with those of corresponding wild-type pigments, we can elucidate the molecular mechanisms of lambda max shifts--and color vision--of vertebrates rigorously.

Amino Acid Sequence↗
PubMed1991

Primary structure of human, chicken, and Xenopus laevis p11, a cellular ligand of the Src-kinase substrate, annexin II.

The p11 protein is a member of the S-100 family of Ca(2+)-binding proteins and serves within the cell as a ligand of the tyrosine kinase substrate, annexin II. To obtain more structural information on this molecule, we have isolated and characterized p11 cDNA clones from several different species. A comparison of the deduced amino acid (aa) sequences reveals that mammalian and avian p11 are highly similar (at least 90% identical at the aa level), whereas p11 from Xenopus laevis shows a considerable degree of sequence variation (the aa sequence identity drops to approx. 60% when compared to mammalian or chicken p11). Interestingly, the C-terminal 18 aa, which are unique to p11 within the S-100 family, show a relatively high conservation among species. This high evolutionary conservation is in line with a structurally and/or functionally important role of this C terminus, e.g., in annexin II binding.

Amino Acid Sequence↗
PubMed2005

PEDF and the serpins: phylogeny, sequence conservation, and functional domains.

Pigment epithelium derived factor (PEDF) is non-inhibitory serpin with neurotrophic and antiangiogenic functions. In this study, we have assembled PEDF sequences for 9 additional species by data base mining and performed cross-species alignment for 14 PEDF sequences to identify conserved structural domains. We found evolutionary conservation of a leader sequence, a single C-terminal glycosylation site, collagen-binding residues, and four specific conserved PEDF peptides. The C-terminus, 384--415 and an N-terminal region 78--95, show close homology with many other serpins, and there is strong conservation of 39 of 51 consensus key residues involved in serpin structure and function. Two peptide regions, 40--67 and 277--301, are unique to PEDF but conserved in all species. Conserved residues at the N-terminus, helix d (hD), and helix A (hA) of PEDF form a structure similar to the heparin-binding groove of other serpins. We identified a motif in PEDF that is homologous to the nuclear localization signals of other proteins. A bitopographical localization of PEDF was confirmed by immunocytochemistry and Western blots. Our results suggest that secretion is required for PEDF's activity, that PEDF can migrate to the nucleus, and that PEDF has structural and functional features more common with inhibitory serpins.

Amino Acid Motifs↗
PubMed2004

Cloning and comparative analysis of the bovine, porcine, and equine sex chromosome genes ZFX and ZFY.

A growing body of evidence suggests the involvement of sex chromosome genes in mammalian development. We report the cloning and characterization of the complete coding regions of the bovine Y chromosome ZFY and X chromosome ZFX genes, and partial coding regions of porcine and equine ZFX and ZFY genes. Bovine ZFY and ZFX are highly similar to each other and to ZFX and ZFY from other species. While bovine and human ZFY proteins are both 801 amino acids long, bovine ZFX is 5 amino acids shorter than human ZFX. Like in humans, both bovine ZFY and ZFX contain 13 zinc finger motifs and belong to the Krueppel family of C2H2-type zinc finger proteins. The internal exon-intron organization of the bovine, porcine and equine ZFX and ZFY genes has been determined and compared. Within this region, the exon lengths and the positions of the splice sites are conserved, further suggesting a high evolutionary conservation of the ZFX and ZFY genes. Additionally, new alternatively spliced forms of human ZFX have been identified.

Amino Acid Sequence↗
PubMed1996

Molecular cloning of a type A chicken corticotropin-releasing factor receptor with high affinity for urotensin I.

The hypothalamic-pituitary-adrenal axis is an essential physiological system in many species. CRF, the major neuropeptide regulating ACTH secretion, is highly conserved in its primary sequence. Evolutionary conservation of the CRF sequence suggests that the CRF receptor (CRF-R) complementary DNA and examined its properties. The avian CRF-R complementary DNA encodes a 420-amino acid protein that is 87-88% identical to those of human, rat, and mouse. Most sequence divergence occurs in the putative signal peptide and the extracellular amino-terminus of the receptor. Five additional amino acids are inserted in the amino-terminus of the cCRF-R. When expressed in COS-7 cells, the cCRF-R binds the CRF and urotensin I radioligands with high affinities. Urotensin I competes for binding to the chicken CRF-R, expressed in COS-7 cells, with an apparent affinity 20 times higher than that of CRF. Both urotensin I and sauvagine were more effective in stimulating cAMP accumulation in COS-7 cells transfected with the cCRF-R than CRF. The effects of CRF and urotensin I on inositol phosphate accumulation were also tested. Urotensin I was an effective as CRF in stimulating inositol phosphate accumulation in COS-7 cells transfected with the cCRF-R. These data suggest that the sequence of the CRF-R is highly conserved from avian to mammalian species and that, despite its high sequence homology to the type A mammalian CRF-R, the ligand binding properties of cCRF-R are similar to those of the type B CRF-R i.e. a higher affinity for urotensin I than for CRF.

Animals↗
PubMed2006

Tissue expression of the mulibrey nanism-associated Trim37 protein in embryonic and adult mouse tissues.

Mutations in the TRIM37 gene underlie mulibrey nanism (muscle-liver-brain-eye nanism), a rare monogenic developmental disorder characterized by severe growth failure, characteristic dysmorphic features, cardiopathy, failure of sexual maturation, and metabolic syndrome. The TRIM37 protein, a member of the tripartite motif subfamily of RING finger proteins, is highly conserved between human and mouse. High evolutionary conservation is seen also at the gene level. We here show that the mouse Trim37 gene presents several alternative splice variants, including a testis-specific transcript with an additional 3' exon. By Northern blot analysis the highest level of Trim37 mRNA was detected in testis and brain. In embryonic tissues, the Trim37 protein was detected in epithelia, including ducts of the developing pancreas, epithelium of the midgut and nasal epithelium. In adult mouse tissues, Trim37 immunoreactivity was detected in the central and peripheral nervous systems, including enteric ganglia, retina, and the adrenal medulla. Moreover, specific cellular populations in the adenohypophysis, pancreatic islets, intestine and gonads showed intense Trim37 staining. Both nuclear and granular cytoplasmic staining patterns were observed. These findings are in agreement with the clinical manifestations of mulibrey nanism and provide a basis for the future analysis of Trim37 knock-out mice.

Alternative Splicing↗
PubMed1999

Comparative sequence of human and mouse BAC clones from the mnd2 region of chromosome 2p13.

The mnd2 mutation on mouse chromosome 6 produces a progressive neuromuscular disorder. To determine the gene content of the 400-kb mnd2 nonrecombinant region, we sequenced 108 kb of mouse genomic DNA and 92 kb of human genomic sequence from the corresponding region of chromosome 2p13.3. Three genes with the indicated sizes and intergenic distances were identified: D6Mm5e (>/=81 kb)-787 bp-DOK (2 kb)-845 bp-LOR2 (>/=6 kb). D6Mm5e is expressed in many tissues at very low abundance and the predicted 526-residue protein contains no known functional domains. DOK encodes the p62(dok) rasGAP binding protein involved in signal transduction. LOR2 encodes a novel lysyl oxidase-related protein of 757 amino acid residues. We describe a simple search protocol for identification of conserved internal exons in genomic sequence. Evolutionary conservation proved to be a useful criterion for distinguishing between authentic exons and artifactual products obtained by exon amplification, RT-PCR, and 5' RACE. Conserved noncoding sequence elements longer than 80 bp with >/=75% nucleotide sequence identity comprise approximately 1% of the genomic sequence in this region. Comparative analysis of this human and mouse genomic DNA sequence was an efficient method for gene identification and is independent of developmental stage or quantitative level of gene expression. [The sequence data described in this paper have been submitted to the GenBank data library under the following accession numbers: AC003061, mouse BAC clone 245c12; AC003065, human BAC clone h173(E10); AF053368, mouse Lor2 cDNA; AF084363, 108-kb contig from mouse BAC 245c12; AF084364, mouse D6Mm5e cDNA.]

Amino Acid Sequence↗