80% [5]) while retaining the characteristic Ig-like folds. The overall Ig-like character imparted to BGP molecules suggests that they function as receptors, perhaps involved in adhesion (23, 37). However, the alternate splicing of the extracellular IIa domain, in combination with two possible intracellular forms, one of which may be phosphorylated (1), suggests that alteration in these molecular structures could play an important role in recognition and signal transduction. Similar observations gave been made for other Ig-like molecules, most notably the fibroblast growth factor receptor (15,25,29).Defining the size and diversity of the BGP family is a first step in exploring a functional role. Toward this end, we surveyed the RNAs of many different normal tissues and transformed cell lines by polymerase chain reaction (PCR) amplification of the specific extracellular and intracellular regions of BGP mRNAs that are known to be alternatively spliced and code for one of several isoforms. By this process, we found additional size classes of amplified products that differ substantially from those previously described. Further characterization of these segments revealed that they code for two novel non-Ig-like extracellular domains derived by alternative splicing fromAlu-like elements, as well as another form that codes for a BGP isoantigen with only an N terminus anchored via a TM domain to a cytoplasmic tail. Some of these forms appear to be represented more in RNAs from tumor-derived cells than in RNAs from normal tissue counterparts, suggesting that the transformed phenotype may contribute to the appearance of new BGP splice variants and their translated polypeptides.The finding of additional novel forms of BGP extends the
Pregnancy-specific beta 1-glycoproteins (PSGs) represent a large group (approximately 12-15) of proteins, related to members of the carcinoembryonic antigen family, that are abundant in placental tissue and in the sera of pregnant women. We describe the isolation and characterization of two additional PSG cDNAs, PSG9 and PSG10, whose transcripts are largely expressed in placental tissue and to a lesser extent in some other cell types, including myeloid cells differentiated to granulocytes. PSG9 and PSG10 are representatives of two distinct classes of PSG protein that have N-termini with or without the Arg-Gly-Asp motif implicated in adhesion. In addition to this distinction at the amino acid level, our analysis of several PSG cDNAs suggests that the transcription units encoding these proteins may be further distinguished in their 3' untranslated sequences, thus suggesting possibilities for transcriptional regulation of the two major protein classes.
Next Generation Sequencing allows for testing and typing of entire genes of the HLA region. A better and comprehensive sequence assessment can be achieved by the inclusion of full gene sequences of all the common alleles at a given locus. The common alleles of DRB5 are undercharacterized with the full exon-intron sequence of two alleles available. In the present study the DRB5 genes from 18 subjects alleles were cloned and sequenced; haplotype analysis showed that 17 of them had a single copy of DRB5 and one consanguineous subject was homozygous at all HLA loci. Methodological approaches including robust and efficient long-range PCR amplification, molecular cloning, nucleotide sequencing and de novo sequence assembly were combined to characterize DRB5 alleles. DRB5 sequences covering from 5'UTR to the end of intron 5 were obtained for DRB5*01:01, 01:02 and 02:02; partial coverage including a segment *
Eight different human biliary glycoprotein (BGP) isoantigens, structurally related members of the carcinoembryonic antigen family, CD66/67 family, and immunoglobulin superfamily, are derived by alternative splicing from a single genomic transcription unit. Novel BGP isoforms have been identified by polymerase chain reaction amplification and by DNA sequencing of amplified cDNA segments. In addition to verifying previously documented BGPs, we describe four new forms, two of which have unusual nonimmunoglobulin exons contributed by inverted Alu repeats. Determination of the genomic DNA sequence encompassing most of the known extracellular and intracellular domains demonstrates that the translatable Alu-like sequences are encoded in bona fide exons. The third novel BGP isoform contains none of the extracellular disulfide-linked immunoglobulin-like domains typical of these molecules but retains N-terminal and intracellular domains, suggesting distinct functions for N-terminal versus other disulfide-linked domains. cDNAs coding for each identified isoform have been transfected into COS7 monkey cells, and the resulting polypeptides are heavily N glycosylated but can be deglycosylated to their expected primary sizes. Many of these deglycosylated forms can be correlated with unique patterns of BGP expression in different cell lines, while in granulocytes, some previously undescribed or alternatively modified forms may predominate. The BGP family represents a potentially large but unknown source of functional diversity among cells of epithelial and hematopoietic origin. The availability of a defined set of expressed of BGP cDNAs should permit critical definition of their function.
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