IDENTIFICATION OF A NEW IMMUNOGLOBULIN SUPERFAMILY PROTEIN EXPRESSED IN BLOOD-VESSELS WITH A HEPARIN-BINDING CONSENSUS SEQUENCE

A novel immunoglobulin-type protein expressed in blood vessels has bee n identified. The cDNA for AAMP (angio-associated, migratory cell prot ein) was first isolated from a human melanoma cell line during a searc h for motility-associated cell surface proteins. Upon analysis of the tissue distribution of AAMP, it was found to be expressed strongly in endothelial cells, cytotrophoblasts, and poorly differentiated colon a denocarcinoma cells found in lymphatics. The sequence of AAMP predicts a protein (M(r) 49,000) with distant identity (25%) to known proteins . It contains immunoglobulin-like domains [one with multiple homologie s to deleted in colon carcinoma (DCC) protein], the WD40 repeat motif, and a heparin-binding consensus sequence. A 1.6-kilobase mRNA transcr ipt of AAMP is detected in tissue culture cell lines and tissues. Affi nity-purified polyclonal antibodies, anti-recombinant AAMP, and anti-p eptide 189 (AAMP derived) recognize a M(r) 52,000 protein in human tis sue and cellular extracts. The protein size is in keeping with the mRN A and predicted sequence. The AAMP-derived peptide, P189, contains a h eparin-binding domain (dissociation constant, 14 pmol) and mediates he parin-sensitive cell adhesion. The shared expression of AAMP in endoth elial cells, trophoblasts, and tumor cells implies a common function i n migrating cells.