Complementary DNA sequence and chromosomal mapping of a human proteoglycan-binding cell-adhesion protein...

We have noticed the presence of a protein with a M(r) of approx 22 kDa in proteoglycan preparations from human fibroblast cultures and speculated that it might be related to a 22-kDa protein from bovine skin (22K) with proteoglycan- and cell-binding properties. Using degenerated oligomers designed from the amino acid sequence of the bovine protein, we amplified and subcloned sequences from human fibroblast and fibrosarcoma cDNA. The three clones that were characterized contain an open reading frame (603 bp) coding for 201 amino acids comprising a secretory leader peptide of 18 amino acids and a secreted part of 183 amino acids with 96% identity to the bovine sequence, indicating that they code for the human homologue ("dermatopontin") of the bovine 22K protein. Expression of dermatopontin is not limited to connective tissue, as Northern blots show specific mRNAs in cultured fibroblasts, muscle, heart, pancreas, and lung. Two species of mRNA (1.0 and 2.2 kb) are present, indicating alternative polyadenylation or alternative splicing. The cDNA clones map to 1q12-q23 in a cell hybrid panel containing specific chromosomal deletions.