Search PubMed⌕ Search

Biomedical subjects

S Surrey

Publications and source records attributed to S Surrey.

At least 73 records · Page 4Linked to original sources
PubMed1993

Effects of beta 6 aromatic amino acids on polymerization and solubility of recombinant hemoglobins made in yeast.

Valine, leucine, tryptophan, and phenylalanine substitutions at the beta 6 position of hemoglobin (Hb) were made using a yeast expression system coupled with a polymerase chain reaction-based mutagenesis strategy. The oxygen affinity and absorption spectra of these mutants were similar to recombinant Hb A except for Hb beta E6W which had a higher absorbance at approximately 280 nm. The deoxy forms of Hb beta E6L and Hb S showed characteristic delay times prior to polymerization. Tetrameric deoxy-Hbs containing tryptophan or phenylalanine at the beta 6 position had higher solubilities and polymerized less readily compared with deoxy-Hb S. However, when oversaturated, these Hbs polymerized without a delay time. These results suggest that Hb beta E6W and Hb beta E6F form polymers upon deoxygenation by a linear polymerization mechanism without nuclei formation. During polymerization, bulky hydrophobic amino acids, like phenylalanine and tryptophan at the beta 6 position, might interact with the acceptor pocket on the surface of an adjacent Hb molecule but may not be able to form stable hydrophobic interactions like beta 6 valine and leucine. Difficulty in insertion of the bulky side chains of these aromatic amino acids into the hydrophobic acceptor pocket on an adjacent tetramer may inhibit nuclei formation prior to polymerization.

Amino Acids↗
PubMed1993

Analysis of delta-globin gene mutations in Greek cypriots.

We recently described four delta-globin gene mutations in Greek Cypriots studied by polymerase chain reaction (PCR) amplification and automated fluorescence-based DNA sequence analysis (Blood 78:3298, 1991). Selective restriction enzyme digestion of PCR products facilitated direct mutation detection. Twenty-eight additional samples from unrelated Cypriots with Hb A2 levels ranging from 0.6% to 3.6% were studied by PCR and showed the following: twelve had the delta 27 (ala-->ser) mutation, one was heterozygous for the delta IVS-2 AG-->GG change, and none had either the delta 116 (arg-->cys) or delta 141 (leu-->pro) mutations. The remaining samples were divided into two groups: 11 with borderline normal Hb A2 values that were not pursued; and four with abnormal Hb A2 values. The delta-globin genes from these four samples were sequenced and the same four changes identified in each: a C-->T at -199, a C-->T at codon 4 (thr-->ile), a silent C-->T at codon 97, and an AT deletion at position 722 in IVS-2. The codon 4 change abolishes a Ple I site whereas the codon 97 creates an Nla III site, thus facilitating rapid identification. All four changes are in cis position, suggesting that the -199 C-->T, the C-->T at codon 97, and the AT deletion in IVS-2 are neutral polymorphisms present on the codon 4 (thr-->ile) chromosome. DNA haplotype analysis suggests all five delta-globin gene mutant alleles arose independently on different chromosomal backgrounds.

Base Sequence↗
PubMed1993

Effects of beta 6 amino acid hydrophobicity on stability and solubility of hemoglobin tetramers.

The relationship between different amino acids at the beta 6 position of hemoglobin and tetramer stability was addressed by a site-directed mutagenesis approach. Precipitation rates during mechanical agitation of oxyhemoglobins with Gln, Ala, Val, Leu and Trp at the beta 6 position increased 2, 5, 13, 21 and 53 times, respectively, compared with that for Hb A. There was a linear relationship between the log of the precipitation rate constant and amino acid hydrophobicity at the beta 6 position, suggesting that enhanced precipitation of oxy Hb S during mechanical agitation results in part from increased hydrophobicity of beta 6 Val. Deoxyhemoglobin solubility increased in the order of beta 6 Ile, Leu, Val, Trp, Gln, Ala and Glu suggesting that hydrophobic interactions between beta 6 Val and the acceptor site of another hemoglobin molecule during deoxy-Hb S polymerization not only depend on hydrophobicity but also on stereospecificity of the amino acid side chain at the beta 6 position. Furthermore, our results indicate that hydrophobic amino acids at the beta 6 position which promote tetramer instability in the oxy form do not necessarily promote polymerization in the deoxy form.

Hemoglobins↗
PubMed1993

Fluorescent approaches to diagnosis of Lesch-Nyhan syndrome and quantitative analysis of carrier status.

Lesch-Nyhan syndrome is an X-linked recessive disorder caused by molecular defects within the HPRT gene. Deletional forms of this syndrome, most of which are inherited, account for 15% of the cases. In addition, a large percentage of cases are due to de novo point mutations. We have used complementary fluorescence-based PCR assays to analyse disease-causing mutations in three unrelated families: (1) inheritance of dye-labelled PCR products of linked polymorphic loci mapping within and flanking the HPRT gene; (2) dye-labelled exon dosage analysis and (3) automated fluorescence-based DNA sequence analysis. Our results using fluorescent, dye-tagged PCR products show that inheritance of two polymorphic small tandem repeats, HPRTB [AGAT]n, mapping within intron 3 of the HPRT gene, and the CA-repeat at DXS294 can be used to establish linkage to the disease. In addition, we modified a previously described PCR protocol to use fluorescent dye-labelled oligoprimers and an ABI Gene Scanner in order to rapidly quantitate deletional forms of Lesch-Nyhan syndrome. Quantitative PCR analysis of individual exons followed by dosage analysis confirmed a deletion encompassing exon 9. A similar approach was used to confirm a previously described HPRT gene duplication involving exons 2 and 3. In this analysis, we co-amplified the HPRTB [AGAT]n and HUMARA [AGC]n repeats and confirmed increased exon dosage in carriers for the duplication. DNA sequence analysis remains the method of choice for delineating new disease-causing mutations, most of which are non-deletional forms of Lesch-Nyhan syndrome. We have also used a cycle-sequencing strategy employing dye-labelled dideoxy terminators and a laser-activated, fluorescence-emission DNA sequencer in order to define carrier status in 10 family members at risk for Lesch-Nyhan syndrome due to a splice donor mutation in intron 7. Our DNA sequence analyses corroborate small tandem repeat (STR) inheritance patterns in this family. Multiple fluorescence-based strategies should facilitate rapid diagnosis of the various Lesch-Nyhan disease-causing mutations.

Adolescent↗
PubMed1993

Differential expression of Fc gamma RIIA, Fc gamma RIIB and Fc gamma RIIC in hematopoietic cells: analysis of transcripts.

Fc gamma receptors (Fc gamma R) are glycoproteins that function in the immune response through their ability to bind the Fc portion of immunoglobulin G. Of the three human Fc gamma R classes, Fc gamma RII is most widely distributed among hematopoietic cells and is the only Fc gamma R class present on platelets and megakaryocytes. There are three different genes coding for Fc gamma RII: Fc gamma RIIA, Fc gamma RIIB and Fc gamma RIIC. Alternative splicing of at least two of these genes results in the production of multiple transcripts. Combining Northern blot analysis with reverse transcription-PCR, we analyzed steady state levels of Fc gamma RII mRNA in the megakaryocytic, myeloid and lymphoid lineages. We determined that megakaryocytic cells predominantly contain Fc gamma RIIA mRNA; Fc gamma RIIA transcripts with and without the transmembrane exon (Fc gamma RIIa1 and Fc gamma RIIa2, respectively) are present in comparable amounts. In contrast, B lymphocytes do not express Fc gamma RIIA mRNAs, but do contain both Fc gamma RIIB transcripts, Fc gamma RIIb1 and Fc gamma RIIb2, as well as the Fc gamma RIIC transcript, Fc gamma RIIc. Myelomonocytic cells contain mRNAs from all three Fc gamma RII genes, predominantly the Fc gamma RIIa1 transcript, both Fc gamma RIIb1 and Fc gamma RIIb2 transcripts and Fc gamma RIIc. Lineage-specific expression of the Fc gamma RII genes implies both differential regulation of expression and differential function in diverse cells.

Antigens, CD↗
PubMed1993

Fluorescence-based RT PCR analysis: determination of the ratio of soluble to membrane-bound forms of Fc gamma RIIA transcripts in hematopoietic cell lines.

We have developed a fluorescence-based RT PCR assay for determination of the ratio of two alternatively spliced transcripts in different cell types. Fluorescence detection, by an automated DNA sequencer, allows enhanced sensitivity and ease of data processing. PCR products are fluorescently tagged using a dye-labeled oligonucleotide primer during the PCR reaction. Assay conditions were first defined so that fluorescence intensity of the PCR products was linear with respect to input RNA and exponential relative to PCR cycle number. Sensitivity and reproducibility of detection were evaluated with serial dilutions of RT PCR reactions. We have applied this assay to an analysis of the lineage-specific expression of two human Fc gamma RIIA transcripts, Fc gamma RIIa1 and Fc gamma RIIa2, in different hematopoietic cell lines. Previously, we noted that when standard RT PCR conditions are used with primers that bracket the TM exon, the pattern of expression of these transcripts as assessed by ethidium bromide staining of agarose gels varied in different hematopoietic cell lineages. Using the fluorescence-based RT PCR method, we now confirm our previous findings and quantitate transcript ratios (Fc gamma RIIa2/Fc gamma RIIa1) in several hematopoietic cell lines. The ratio varies from 0.70 (41% Fc gamma RIIa2) in the erythroleukemic cell line HEL, to 0.14 (12% Fc gamma RIIa2) in the monocytic cell line U937, to 0.07 (6% Fc gamma RIIa2) in the multipotential cell line K562. This fluorescent RT PCR method provides a general approach to quantitating mRNA levels and ratios of PCR products in other gene systems.

Alternative Splicing↗
PubMed1993

Hb Shelby [beta 131(H9)Gln-->Lys] in association with Hb S [beta 6(A3)Glu-->Val]: characterization, stability, and effects on Hb S polymerization.

When first tested for abnormal hemoglobins, a 2-year-old boy, appeared to have Hb F, Hb S and Hb A2. Confirmatory testing revealed a beta chain variant inherited from his father and beta S from his mother. Analysis of tryptic peptides in conjunction with automated DNA sequence analysis showed that the variant hemoglobin was Hb Shelby [beta 131(H9)Gln-->Lys (CAG-->AAG)]. Heat and mechanical stabilities of various liganded Hb Shelby tetramers were compared to those of Hb A and Hb S. Oxy-Hb Shelby precipitated more readily than oxy-Hb A, but was much more stable than oxy-Hb S during mechanical agitation. In contrast, oxy-Hb Shelby was much less stable than oxy-Hb A and oxy-Hb S following heat treatment. Met-Hb Shelby was most unstable compared to other liganded forms of Hb Shelby, while deoxy- and carbonmonoxy-forms of Hb Shelby showed similar heat-induced precipitation rates. These data indicate that heat instability of Hb Shelby is accompanied by heme oxidation, and that denaturation by mechanical agitation occurs in the absence of heme oxidation. Hb Shelby, like Hb A, can form hybrids with Hb S which participate in polymer formation in vitro. However, Hb S/Hb Shelby hybrids copolymerized with Hb S less than A/S hybrids. Since the patient's MCHC value is normal, this finding coupled with the elevated Hb A2 and Hb F levels, both of which are known to inhibit polymerization of Hb S, may contribute to the patient's mild clinical presentation.

Base Sequence↗
PubMed1993

A soluble form of the human Fc receptor Fc gamma RIIA: cloning, transcript analysis and detection.

The Fc gamma receptors (Fc gamma R) are glycoproteins that bind the Fc region of immunoglobulin G. Human hematopoietic cells express three biochemically distinct classes of Fc gamma receptors: Fc gamma RI (CD64), Fc gamma RII (CD32) and Fc gamma RIII (CD16). Complementary DNA (cDNA) clones for each of the human Fc gamma receptors have been isolated from myeloid and lymphoid cells. We describe the isolation and characterization of four Fc gamma RII clones from a cDNA library obtained from a megakaryocyte-like cell line, human erythroleukemia (HEL). Three clones encode the Fc gamma RIIA transmembrane (TM) form, while one novel clone lacks the TM region but retains the cytoplasmic domain. By conducting reverse transcription coupled to polymerase chain reaction (PCR), we found transcripts coding for this unique form of receptor in RNA from platelets, HEL cells and a second megakaryocyte-like cell line, CHRF-288-11. These results were confirmed by RNase protection analysis of RNA from HEL cells. The structure of the novel cDNA suggested that it codes for a soluble form of Fc gamma RIIA. A soluble Fc gamma RII protein was detected in the conditioned medium from HEL cells but not from the Fc gamma RII-negative T cell line, Jurkat, by immunoprecipitation with the anti-Fc gamma RII monoclonal antibody (mAb), IV.3. The immunoprecipitated protein was of the expected size for a soluble Fc gamma RII lacking the TM region but retaining the cytoplasmic domain. Soluble Fc gamma RIIA may be important in modulating the interaction between immune complexes and membrane-associated Fc gamma RII.

Amino Acid Sequence↗
PubMed1992

Characterization of the 5'-flanking transcriptional regulatory region of the human Fc gamma receptor gene, Fc gamma RIIA.

The human Fc gamma receptor gene Fc gamma RIIA is expressed in platelets, neutrophils, monocytes and macrophages. Understanding the regulation of expression of Fc gamma RIIA will enhance our knowledge of regulated gene expression and immune function in these cells. We cloned a 3.65 kb region of the 5' end of the Fc gamma RIIA gene and characterized 3.4 kb of previously unreported sequence of the 5'-flanking region. Primer extension studies and RNase protection analyses of mRNA from HEL, K562 and U937 cells revealed multiple transcription start sites. One transcription start site mapped to a 5'-untranslated (5'UT) exon approximately 1 kb 5' to the ATG translation initiation codon, while a second start site mapped near the ATG codon. Reverse transcription combined with PCR (RT-PCR) employing an oligonucleotide in the putative 5'UT exon and an antisense oligonucleotide in the translated region yielded products which confirm that transcription starts in this 5'UT exon 881 bp upstream of the ATG codon. Sequence analysis of the RT-PCR products showed two related RNA splice products which use alternative 3'-consensus AG splice acceptor sites. Fc gamma RIIA mRNA thus has three distinct potential 5'UT regions, two alternatively spliced forms from the start site in the 5'UT exon and the third from the start site near the ATG codon. Comparisons of the human Fc gamma RIIA 5'-flanking region with human Fc gamma RI and mouse Fc gamma RII beta genes as well as with other genes expressed in megakaryocytes, neutrophils and monocytes reveal structural similarities and shared promoter elements.

Antigens, CD↗
PubMed1992

Fluorescence-based, multiplex allele-specific PCR (MASPCR) detection of the delta F508 deletion in the cystic fibrosis transmembrane conductance regulator (CFTR) gene.

Cystic fibrosis (CF) is a common genetic disorder in Caucasians, and in some populations 70% of cases are associated with a 3 base pair (bp) deletion (delta F508) in the CFTR gene. We have implemented a fluorescence-based, multiplex allele-specific polymerase chain reaction (MASPCR) assay for deletion of the delta F508 mutation. Different allele-specific fluorescently-tagged primers are used in the PCR reaction to distinguish between normal and delta F508 alleles. Fluorescent PCR products are then visualized in a single lane on an agarose gel following electrophoresis combined with real-time multicolour fluorescence detection. The approach simplifies diagnosis of the most common mutation in the CFTR gene, and holds promise for a multiplex allele-specific, fluorescence-tagged gene amplification strategy for detection of additional CF mutations which may result in more cost-effective testing without increasing the risk of missed or erroneous diagnoses.

Alleles↗
PubMed1992

Oxygen binding and other physical properties of human hemoglobin made in yeast.

Wagenbach et al. (1991, BioTechnology, 9, 57-61) have recently developed a system for producing soluble recombinant tetrameric hemoglobin in yeast: hemoglobin begins to appear 4-5 h after induction with galactose, alpha- and beta-globin chains fold in vivo and endogeneously produced heme is incorporated into hemoglobin tetramers. We have further characterized the oxygen-binding properties, as well as the tetramer stability, of recombinant human Hb A made in yeast. After purification by ion-exchange chromatography, a single band at the same position as normal human Hb A was obtained using cellulose acetate electrophoresis. Although the oxy and deoxy forms of purified recombinant Hb A made in yeast were spectrophotometrically identical to native human Hb A, the oxygen-binding curve was shifted slightly left of that for native human Hb A. Further purification of recombinant hemoglobin by FPLC revealed two fractions: one (fraction B) with low cooperativity and high oxygen affinity, and the other (fraction A) with almost identical cooperativity and oxygen affinity compared with native human Hb A. The Bohr effect of fraction A was also identical to native human Hb A. Hemoglobin in fraction B with lowered cooperativity precipitated approximately 1.5 times faster than normal human Hb A during mechanical agitation, while hemoglobin in fraction A with normal cooperativity precipitated with kinetics identical to native human Hb A. These results suggest that some of the recombinant molecules made in yeast fold improperly, and that these molecules may exhibit decreased cooperativity for oxygen binding and decreased stability.(ABSTRACT TRUNCATED AT 250 WORDS)

Allosteric Regulation↗
PubMed1992

Detection of the most common mutations causing beta-thalassemia in Mediterraneans using a multiplex amplification refractory mutation system (MARMS).

A rapid, simple, cost-effective, non-radioactive method for detection of the most common mutations causing beta-thalassemia in Mediterranean people has been developed by combining multiplexing with the amplification refractory system. This approach, the multiplex amplification refractory mutation system (MARMS), provides an easy assay for direct detection of normal and mutant beta-globin genes in homozygotes and heterozygotes. The strategy involves multiplex PCR of four of the five regions of interest within the beta-globin gene in a single reaction containing a common oligoprimer and either the normal or mutant oligonucleotides corresponding to IVS-1 nucleotide 1 or IVS-1 nucleotide 6, IVS-1 nucleotide 110, codon 39, and IVS-2 nucleotide 1 regions. Primers are chosen so that the sizes of the four PCR products differ, thereby facilitating detection on agarose gels following amplification. Patient samples are primed with either four normal or four mutant oligonucleotide mixtures and the common oligoprimer, and PCR products run in parallel on gels to detect band presence or absence. This approach simplifies mutation detection and shows promise for automation employing fluorescent-tagged primers.

Alleles↗
PubMed1991

Identification of four novel delta-globin gene mutations in Greek Cypriots using polymerase chain reaction and automated fluorescence-based DNA sequence analysis.

The molecular basis of most beta-thalassemia syndromes has been defined, while the spectrum of mutations causing delta-thalassemia is not well characterized. In an attempt to identify such mutations, the region encompassing the delta-globin gene from three Greek Cypriot families suspected of having delta-thalassemia was amplified by polymerase chain reaction (PCR), and DNA sequence determined using an automated fluorescence-based sequencer. Four novel mutations were identified: a G----T change at codon 27 that results in an alanine to serine change; a C----T change at codon 116 converting arginine to cysteine; a T----C change at codon 141 converting leucine to proline; and an AG----GG change at the consensus 3'-acceptor site in IVS-2. While the latter is clearly a thalassemic mutation, the low hemoglobin A2 in the first three may be due to either decreased production or instability of the altered delta-globin chain. All four mutations may be detected by PCR amplification of genomic DNA followed by restriction enzyme digestion. Two mutations abolish restriction sites while two create new cleavage sites. Screening for molecular defects that cause delta-thalassemia or unstable delta-globin by PCR amplification and restriction enzyme digestion will lead to correct diagnosis of beta/delta-thalassemia compound heterozygotes and improved genetic counseling.

Autoanalysis↗
PubMed1991

The Xmn I site (-158, C----T) 5' to the G gamma gene: correlation with the Senegalese haplotype and G gamma globin expression.

There are three major African haplotypes associated with the sickle mutation: Benin (#19), Senegalese (#3), and Central African Republic (#20). Previous studies have suggested that the Xmn I site (-158 bp 5' to the G gamma gene) is associated with elevated levels of G gamma and with the Senegalese haplotype, while other investigators questioned this association. In order to clarify the issue, we have determined beta haplotypes, tested for the presence of the Xmn I site, and measured Hb F and G gamma expression levels in 143 American Black patients with sickle cell anemia. Haplotypes were determined using eight polymorphic sites in the beta-like globin gene cluster: Hinc II 5' to epsilon, Hind III in IVS-II G gamma and A gamma, Hinc II within and 3' to psi beta, Ava II in IVS-II of beta, and Hpa I and Bam HI 3' to beta. The G gamma /A gamma ratio was analyzed by high performance liquid chromatography using a C18 column. The Xmn I site was present in all 31 chromosomes with the Sengalese haplotype. Of the remaining 255 chromosomes with other haplotypes, only 2 (0.8%) had the Xmn I site present. There was significant correlation between the presence of the Xmn I site and increased G gamma /A gamma ratio in a dose-dependent manner. The Hb F level was not significantly increased in the presence of the Xmn I site. The data indicate that the Xmn I site maintains a G gamma /A gamma ratio typical of fetal life but does not necessarily cause elevation of Hb F. The latter seems to depend on factors other than the Xmn I site.

Adolescent↗
PubMed1991

Polymerization and solubility of recombinant hemoglobins alpha 2 beta 2 (6Val) (Hb S) and alpha 2 beta 2(6Leu) (Hb Leu).

In an effort to clarify the role of amino acid hydrophobicity at the beta 6 position in sickling we have made recombinant hemoglobin tetramers containing beta 6 Val (Hb S) and beta 6 Leu (Hb Leu). Recombinant Hb S and Hb Leu had the same electrophoretic mobility, chromatographic behavior, and absorption spectrum. The deoxy form of both tetramers polymerized in high phosphate buffer (1.8 M) and exhibited distinct delay times prior to polymerization. The kinetics of polymerization for recombinant and native Hb S were similar, while recombinant Hb Leu polymerized more readily. The solubility of deoxy Hb Leu was less than deoxy Hb S, indicating that rapid polymerization and decreased solubility of deoxyhemoglobin is accelerated with increasing hydrophobicity at the beta 6 position.

Amino Acid Sequence↗
PubMed1991

A greater than 200 kb deletion removing the entire beta-like globin gene cluster in a family of Irish descent.

We describe a new deletional form of gamma delta beta-thalassemia segregating in two generations of a family of Irish descent. Affected family members present with a beta-thalassemia minor phenotype, normal Hb A2 and Hb F levels. Genomic blotting analyses on DNA from affected family members show heterozygosity for a large deletion beginning at least 15 kb upstream of the 5' endpoint of the gamma delta beta-thalassemia-1 deletion, extending through the entire beta-like globin gene cluster, and continuing for at least 10 kb beyond the 3' endpoint of the deletion associated with the Spanish form of delta beta 0-thalassemia. This deletion is among the largest described so far, and removes at least 205 kb encompassing the entire beta-like globin gene cluster on chromosome 11.

Adult↗
PubMed1990

Structural and functional comparison of the genes for human platelet factor 4 and PF4alt.

Platelet factor 4 (PF4) is a 70 amino acid heparin-binding protein released from the alpha-granules of activated platelets. Its exact biologic function is not known, although PF4 is a member of a multigene family involved in chemotaxis, coagulation, inflammation, and cell growth. We previously cloned the cDNA for human PF4 from a human erythroleukemic (HEL) cell expression library. We now report the isolation and sequence determination of the gene for human PF4. This gene contains three exons and spans approximately 1,000 basepairs (bp). Concurrently, we have cloned a highly homologous gene that we have called PF4alt. We show that PF4 and PF4alt are non-allelic genes: the human PF4 gene is encoded on a 10 kilobasepairs (kb) EcoRI fragment, and its DNA sequence agrees with protein and cDNA data for PF4, while PF4alt is encoded in a polymorphic 3 or 5 kb EcoRI fragment. Compared with PF4, this gene has 14% DNA and 38% amino acid divergence in the signal peptide region, and 2.6% DNA and 4.3% amino acid divergence in the coding region of the mature protein. PF4alt contains three amino acid substitutions (P58----L, K66----E, and L67----H) near the C-terminus, in a region known to be critical for PF4 function. Primer extension studies show the 5'-untranslated region of PF4 is 73 bp long. A TATA box is present 30 bp 5' to the transcription start site. A 90 bp stretch of pyrimidines (including 53 consecutive thymidine residues) begins at -227 bp and is analogous to a similar region of 30 residues 5' to the rodent PF4 gene. This pyrimidine-rich region is absent from the PF4alt gene; however, DNA homology exists between the two human genes in the 5'- and 3'-flanking regions and extends for over 3.6 kb. Alternating purine/pyrimidine tracts occur both 5' and 3' to PF4 and PF4alt but do not define the endpoints of the gene duplication, which extend beyond these sequences at least at the 5' end. Northern blot analysis using gene-specific oligonucleotides and platelet RNA showed an 800 or 900 nucleotide (n) message for PF4 and PF4alt, respectively. Northern blot and primer extension studies show that steady-state platelet PF4 mRNA levels are approximately one magnitude greater than PF4alt mRNA levels. Thus, these studies demonstrate that PF4alt mRNA is expressed in platelets. Whether PF4alt protein is expressed remains to be determined, and the nature of its biologic function needs to be studied.(ABSTRACT TRUNCATED AT 400 WORDS)

Base Sequence↗