Sequence of human syndecan indicates a novel gene family of integral membrane proteoglycans.

摘要: The structure of human syndecan, an integral membrane proteoglycan, has been determined by cloning its full-length cDNA, which codes for the entire 310-amino acid-long core protein, including NH2-terminal signal peptide. Similar to mouse syndecan (Saunders, S., Jalkanen, M., O'Farrell, and Bernfield, M. (1989) J. Cell Biol. 108, 1547-1556), protein can be divided into three domains: a matrix-interacting ectodomain containing putative glycosaminoglycan attachment sites, 25-residue hydrophobic membrane-spanning domain, 34-residue cytoplasmic domain. Several interesting conserved structures were revealed comparing sequence murine one. (i) Although ectodomains are only 70% identical, all sites identical (two them belong consensus SGXG others (E/D)GSG(E/D), as also (ii) single N-glycosylation site (iii) proteinase-sensitive dibasic RK adjacent extracellular face transmembrane Furthermore, (iv) domain is 96% change in was alteration alanine residue glycine; finally, (v) 100% 3 identically located tyrosine residues. Comparison domains third cell-surface 48K5 from lung fibroblasts (Marynen, P., Zhang, J., Cassiman, Vanden Berghe, H., David, C. Chem. 264, 7017-7024), indicates that similar this molecule regardless presence totally nonhomologous ectodomain. Thus, unique these proteoglycans, we propose members novel gene family syndecans.