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S S Li

Publications and source records attributed to S S Li.

At least 109 records · Page 6Linked to original sources
PubMed1987

Complete nucleotide sequence of the mouse lactate dehydrogenase-A functional gene: comparison of the exon-intron organization of dehydrogenase genes.

The complete sequence of 12,851 nucleotides of the mouse lactate dehydrogenase-A (LDH-A) gene has been determined. It includes eight exons, seven introns, promoter and regulatory regions. The B1 repetitive elements present in intron III and VI are oriented in opposite orientation, and they share 72% sequence homology. The exon-intron organization of mouse LDH-A gene is compared with the organizations of other dehydrogenase genes, and the molecular evolution of the nicotinamide adenine dinucleotide binding domains is discussed.

Animals↗
PubMed1986

Nucleotide sequence of the putative regulatory region of mouse lactate dehydrogenase-A gene.

The nucleotide sequence of approx. 3 kilobases including the regulatory region, a non-coding exon and the first protein-coding exon from mouse lactate dehydrogenase-A (LDH-A) gene has been determined. The putative initiation sites of transcription and translation were deduced by comparing the nucleotide sequence of mouse LDH-A gene with those of a mouse LDH-A processed pseudogene and the LDH-A full-length cDNAs from rat and human. The tentative TATA and CAAT boxes, and the hexanucleotides CCGCCC have been identified. The sequence of AAATCTTGCTCAA of mouse LDH-A gene has also been found to show striking homology to the cyclic AMP-responsive sequences of eukaryotic genes regulated by cyclic AMP. It has been reported previously that the protein-coding sequence of mouse LDH-A gene is interrupted by six introns and the 3' untranslated sequence of 485 nucleotides is not interrupted [Li, Tiano, Fukasawa, Yagi, Shimiza, Sharief, Nakashima & Pan (1985) Eur. J. Biochem. 149, 215-225]. An additional intron of 1653 base-pairs was found in the 5' untranslated sequence of 101 nucleotides at 24 nucleotides upstream to the translation start site. Thus, mouse LDH-A gene containing seven introns spans approx. 11 kilobases and its length of mature mRNA is 1582 nucleotides, excluding the poly(A) tail.

Animals↗
PubMed1986

Identification of the mouse low-salt-eluting single-stranded DNA-binding protein as a mammalian lactate dehydrogenase-A isoenzyme.

A 36,000-Mr protein purified from mouse myeloma on the basis of selective binding to a single-stranded DNA (ssDNA)-cellulose column has been identified as the lactate dehydrogenase A (LDH-A) subunit. A homogeneous preparation of this mouse myeloma ssDNA-binding protein, termed the 'low-salt-eluting protein', was found to possess LDH activity, and rabbit antiserum prepared against this protein was shown to cross-react with purified 36,000-Mr LDH-A subunits from mouse and bovine sources. In addition, bovine and human LHD-A4 isoenzymes were shown to be capable of binding ssDNA. These enzymic and immunological identities with LDH-A were not observed with purified helix-destabilizing protein 1 from mouse myeloma. A model for ssDNA-LDH binding is discussed.

Animals↗
PubMed1986

Molecular evolution of mammalian lactate dehydrogenase-A genes and pseudogenes: association of a mouse processed pseudogene with a B1 repetitive sequence.

A mouse genomic clone containing a lactate dehydrogenase-A (LDH-A) processed pseudogene and a B1 repetitive element was isolated, and a nucleotide sequence of approximately 3 kb was determined. The pseudogene and B1 element are flanked by perfect 13-bp repeats, and the B1 sequence starts at 14 nucleotides 3' to the presumptive polyadenylation signal of the pseudogene. The nucleotide sequences of the LDH-A genes and processed pseudogenes from mouse, rat, and human were compared, and a phylogenetic tree was constructed. The rate and pattern of nucleotide substitutions in the LDH-A pseudogenes are similar to previously reported results (Li et al. 1984). The average rate of nucleotide substitutions in the LDH-A pseudogenes is 4.3 X 10(-9)/site/year. The substitutions of C----T and G----A are most frequent, and A----G substitutions are relatively high. The rate of synonymous substitutions in the LDH-A genes is 5.3 X 10(-9), which is not significantly higher than the average rate of 4.7 X 10(-9) for 35 mammalian genes. The rate of nonsynonymous substitutions in the LDH-A genes is 0.20 X 10(-9), which is considerably lower than the average rate of 0.88 X 10(-9) for 35 mammalian genes. Thus, the mammalian LDH-A gene appears to be highly conserved in evolution.

Animals↗
PubMed1985

Protein structure and gene organization of mouse lactate dehydrogenase-A isozyme.

The complete covalent structure of the 331 amino acids of mouse lactate dehydrogenase (LDH) A4 isozyme has been determined by sequence analyses of both the protein and the genomic DNA. The mouse LDH-A gene spans a length of at least 7000 bases from the translation initiation codon ATG to the end of the 3' untranslated region, and it contains six introns that interrupt the protein-coding sequence. The relationships between the exon-intron organization of LDH-A gene and the structural-functional domains of the protein are discussed.

Amino Acid Sequence↗
PubMed1985

Nucleotide sequences of the cDNA and an intronless pseudogene for human lactate dehydrogenase-A isozyme.

Eight cDNA clones for lactate dehydrogenase-A isozyme (LDH-A) were isolated from a human fibroblast cDNA library, characterized, and no sequence heterogeneity was found. Four cDNA clones appear to contain nearly full-length cDNA inserts and the complete nucleotide sequence of 1710 base pairs consists of the protein-coding sequence (999 base pairs), the 5' (97 base pairs) and 3' (565 base pairs) untranslated regions and poly(dA) tail (49 base pairs). The predicted amino acid sequence of the human LDH-A polypeptide shows 92% homology (27 differences out of 331 amino acids compared) with that of the pig LDH-A subunit determined by direct protein sequencing [Kiltz et al. (1977) Hoppe-Seyler's Z. Physiol. Chem. 358, 123-127]. Human genomic clones containing an LDH-A pseudogene were isolated and the nucleotide sequence of 1635 base pairs from an intronless pseudogene was determined. The presence of two termination codons, two deletions of three nucleotides each and the replacement of three arginine residues at the active site (nos 98, 105 and 168) by other amino acids renders its coding region incapable of producing a functional LDH-A protein. A comparison between human LDH-A cDNA and the pseudogene sequences reveals 12.9% differences (114 transitions, 65 transversions and 36 deletions/insertions). Further, only four out of the 25 dCpdG dinucleotides present in the cDNA sequence remain unchanged, although the sequences possess 87.1% homology.

Amino Acid Sequence↗
PubMed1985

Isolation and characterization of a cDNA and a pseudogene for mouse lactate dehydrogenase-A isozyme.

A mouse lactate dehydrogenase-A cDNA was isolated and it was shown to contain the 393bp of the protein-coding sequence and 488bp of the 3' untranslated region. The amino acid sequence deduced from its open reading frame provided independent evidence for the sequence of residues 201-331 of mouse LDH-A subunit (muscle). This cDNA clone was used as a probe to isolate a mouse genomic clone containing a truncated, processed LDH-A pseudogene. This pseudogene showed 81.6% homology at 713 positions compared with the LDH-A cDNA sequence. The divergence of this pseudogene was estimated to have occurred 39 million years ago.

Animals↗
PubMed1984

Immunologically reactive tryptic fragments of human prostatic acid phosphatase.

Three peptide fragments (designated II, III and IV) of human prostatic acid phosphatase (PAP) were isolated to homogeneity from a limited tryptic hydrolysate of PAP by gel filtration on Sephadex G-100, followed by chromatography on DEAE-cellulose and Sephadex G-75. The homogeneity was confirmed by disc poly-acrylamide-gel electrophoresis. The Mr values were 32 500, 25 000 and 11 000 as estimated by gel filtration and sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. Immunoprecipitation study revealed that only fragment II formed an immune precipitate with anti-PAP antibodies. Fragment II exhibited 45% of maximum inhibitory activity on the reaction between PAP and goat anti-PAP IgG (immunoglobulin G) antibodies (or rabbit anti-PAP antibodies), whereas fragments III and IV demonstrated 24% (or 23%) and 29% (or 27%) inhibition respectively. A mixture of these three tryptic fragments of PAP result in 96% (for goat anti-PAP antibodies) and 94% (for rabbit anti-PAP antibodies) inhibitory activities, which were equivalent to the sum of maximum inhibitory activity of the three fragments individually. The results demonstrated that these three tryptic peptide fragments carried all the antigenic active sites of the native PAP, and suggested that the entire molecule of human PAP comprised a minimum of four distinguishable, nonoverlapping antigenic determinants. These three fragments also were shown to retain all the disulphide bonds of the native PAP, and thus were useful reagents for the elucidation of PAP molecular structure.

Acid Phosphatase↗
PubMed1983

Purification and characterization of ribonucleases from human seminal plasma.

Four ribonucleases (RNAases I-IV) have been purified to homogeneity from human seminal plasma by precipitation with 40-75%-satd. (NH4)2SO4, followed by chromatographies on concanavalin A-Sepharose 4B, DEAE-cellulose phosphocellulose, agarose-5'-(4-aminophenylphospho)uridine 2'(3')-phosphate (RNAase affinity column) and Sephadex G-75 or G-100. The homogeneity of these RNAases was confirmed by polyacrylamide-gel electrophoresis. Mr values for these purified RNAases were 78 000, 16 000, 13 300 and 5000 as estimated by gel filtration. Enzyme activities of RNAases I, III and IV were inhibited by Mn2+, Zn2+ and Cu2+ and activated by Na+, K+, Ba2+, Mg2+, Fe2+ and EDTA, whereas that of RNAase II was inhibited by Ba2+, Mg2+, Fe2+, Mn2+, Zn2+ and Cu2+ and activated by Na+, K+ and EDTA. RNAases I, II and IV demonstrated a higher affinity for poly(C) and poly(U) or yeast RNA, whereas RNAase III preferentially hydrolysed poly(U) over poly(C) and yeast RNA. In the presence of 5 mM-spermine, RNAase I was dissociated to a low-Mr (5000) enzyme with an increase in total RNAase enzymic activity. Xenoantiserum to each RNAase was raised and evaluated by immunoprecipitation and immunohistochemical methods. Anti-(seminal RNAase III) antiserum showed no immunological cross-reaction with RNAases of other human origin, whereas anti-(seminal RNAase I), -(RNAase II) and -(RNAase IV) antisera exhibited indistinguishable immunological reactions with serum RNAase and other human RNAases, except that anti-(seminal RNAase I) and -(RNAase antisera IV) did not react with pancreatic RNAases. Seminal RNAases I and IV were identical immunologically as shown by anti-(RNAase I) and anti-(RNAase IV) in immunodiffusion. Immunohistochemical study revealed that, among human tissues examined, only prostate expressed seminal RNAase III. These results suggested that human seminal RNAase I may be an aggregated molecule of RNAase IV and that seminal RNAases II and IV are similar to serum RNAases, whereas seminal RNAase III is a prostate-specific enzyme.

Amino Acids↗
PubMed1983

Molecular features and immunological properties of lactate dehydrogenase C4 isozymes from mouse and rat testes.

With the use of a computer graphics system, spacefilling models of mouse and rat testis lactate dehydrogenase C4 (LDH-C4) isozymes were constructed from amino acid sequence and published x-ray diffraction data. Thirty-two residues that differ between the mouse and rat LDH-C4 sequences are also displayed on the monomeric and tetrameric lactate dehydrogenase molecules. Immunological properties of mouse and rat LDH-C4 isozymes are compared and related to these 32 differences. Possible relationships between the structure, especially the amino acid sequence, and the unique enzymatic properties of LDH-C4 isozymes are also discussed.

Amino Acid Sequence↗