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A possible involvement of HTLV-1-related endogenous sequence 1 (HRES-1) in autoimmune diseases has been recently reported. In primate cells, PCRs and RT-PCRs using specific primers reveal the presence and the transcription of gag-related sequences. However antisera generated against selected HRES-1 peptides failed to detect a 28-kDa protein deduced from the translated gag ORF and described previously. Such discordant results led us to perform DNA cloning and sequencing of LTR- and gag-related nucleotidic fragments. Repeated sequence analyses on distinct samples revealed frameshift mutations in the gag and LTR ORFs. Our sequence analyses detected a stop codon in the gag-related ORF, which is inconsistent with the expression of a 28-kDa protein. Instead of the two ORFs previously found, our gag-related region contained three ORFs. One of them demonstrated higher nucleotidic and peptidic homologies with the p19 gag of HTLV-I. However, the molecular analyses of our new sequence did not show evidence of potent translation capacities.

The MUC3 gene encodes a large, glycosylated mucin produced by intestinal epithelial cells to form a protective barrier against the external environment. Recently published cDNA sequences for the carboxyl-terminal region of MUC3 polypeptide indicated that rodent Muc3 possesses two epidermal growth factor (EGF)-like domains, and putative transmembrane and cytoplasmic domains, whereas the sequence of human MUC3 predicted termination after the first EGF-like domain. Here we describe the complete genomic sequence encompassing the carboxyl terminal region of human MUC3, revealing the boundaries of 11 exons. RT-PCR and cDNA library cloning experiments indicate that the gene is alternatively spliced, yielding a major membrane-bound form as well as multiple soluble forms. Thus, this work indicates that both membrane-bound and soluble MUC3 mucin proteins are produced by alternative splicing of a single gene. A potentially important polymorphism involving a Tyr residue with a proposed role in signalling is described as well., (Copyright 1999 Academic Press.)

MUC5B gene is one of the four human mucin genes mapped to chromosome 11p15. The identification of three potential Sp1 binding sites located between the tandem repeat and the 3' end of MUC5B suggests a possible regulatory role for this region. In this report we show by electrophoretic mobility shift assay that only one potential Sp1 binding site (NAU62) leads to a specific interaction with a nuclear factor from HT-29 MTX cells which does not exist in parental HT-29 cells. By using mutated versions of NAU62, an 18 mer sequence within this later was shown to be directly involved in the interaction. The nuclear factor called NF1-MUC5B which binds to this element has a Mr of 42000 and is not Sp1. These results suggest that MUC5B contains a sequence in its 3' region that might act as a cis-element. This report opens the field of transcriptional regulation of human mucin genes encoding secreted mucins.

A lambda gt11 cDNA library constructed from human tracheo-bronchial mucosa was screened with a polyclonal antiserum raised to chemically deglycosylated pronase glycopeptides from human bronchial mucins. Out of 20 positives clones, one partial cDNA clone was isolated and allowed to map a novel human tracheo-bronchial mucin gene. It contains 48 nucleotide tandem repeats quite perfectly identical which encodes a protein containing about 50% of hydroxy amino-acids. This clone hybridized to polydisperse messages produced by human tracheo-bronchial and human colonic mucosae. The gene (proposed name MUC 4) from which cDNA is derived maps to chromosome 3.

Nine variant specific surface antigens were purified from clones of Trypanosoma equiperdum and characterized by amino acid analysis, isoelectric focusing and circular dichroism. The molecules showed extensive differences in their isoelectric points, and by comparison with the corresponding amino acid compositions, this variation seemed to be due to different amide contents. Circular dichroism data allowed one to divide the molecules into 4 groups according to their respective percentages in alpha-helical and beta-sheet structure.