MOLECULAR-CLONING OF HUMAN MUC3 CDNA REVEALS A NOVEL 59 AMINO-ACID TANDEM REPEAT REGION

The human MUC3 gene is highly c expressed in small intestine and gallb ladder. Thus far only 646 basepairs of its cDNA encoding 17 amino acid repeats have been cloned. In order to further clone the human MUC3 cD NA, a human small intestinal cDNA library was constructed and screened with a cDNA probe encompassing the 17 amino acid tandem repeat region of human MUGS. In two subsequent screenings of the library resulting positive clones were used as probes. In total, 27 partial MUC3 cDNA cl ones were isolated and sequenced that define a semi-unique region and a novel 177 nucleotide tandem repeat region, located upstream of the r egion encoding the 17 amino acid tandem repeats. The 177 nucleotide re peat region is at least 5 kb in length and encodes 59 amino acid repet itive peptides with a consensus sequence of VSTTPVASSEASTLSTTPVDTSTPVT TSTQASSSPTTAEGTS MPTSTPSEGSTPLTSMP, that is notably different from the 17 amino acid repeat of MUC3 or any other known mucin repeat. (C) 199 7 Academic Press.