Degenerate 87-base-pair tandem repeats create hydrophilic/hydrophobic alternating domains in human mucin peptides mapped to 11p15

A human tracheobronchial lambda gt 11 cDNA library was screened using antiserum prepared against the deglycosylated protein backbone of human tracheobronchial mucins. Two cDNAs, designated JER 28 and 57, obtained from this immunoscreening, were used to isolate two other cDNA clones, JUL 7 and JUL 10, from a human tracheobronchial lambda gt 10 cDNA library. These four clones (561, 1830, 1631 and 991 bp), which mapped to chromosome 11p15, were all found to contain degenerate 87-base-pair tandem repeats which encode non-repetitive peptides. Numerous deletions or insertions in an otherwise virtually perfect 87-base-pair tandem repeat create many shifts in reading frame which completely destroy the repetitive peptide structure. The peptide is composed of alternate hydrophobic and hydrophilic domains which probably differ in the extent to which they are glycosylated. The mRNAs are expressed both in the respiratory and in the digestive tracts. These human mucin probes may be important in assessing the abnormal mucins associated with inflammatory diseases or carcinoma from human mucosae.