GPC6, a novel member of the glypican gene family, encodes a product structurally related to GPC4 and is colocalized with GPC5 on human chromosome 13

Glypicans are a family of cell surface heparan sulfate proteoglycans that a ppear to play an important role in cellular growth control and differentiat ion, as is supported by the observation that mutations in GPC3 are responsi ble for Simpson-Galabi-Behmel syndrome (SGBS) in humans. Recently it has be en shown that the GPC4 gene is tightly clustered with GPC3 on the X chromos ome and that some patients with SGBS apparently have deletions affecting bo th genes. We report here the identification of a human cDNA encoding a nove l glypican family member, glypican-6. This cDNA encodes a predicted protein of 554 amino acids and is structurally analogous to other members of the g lypican gene family, but most highly related to glypican-1. A single GPC6 m RNA of 6.2 kb is detected most abundantly in the ovary, liver, and kidney, with lower levels of mRNA expression also detected in a wide range of other adult tissues. Radiation hybrid analysis mapped the GPC6 gene to human chr omosome 13 very near the GPC5 gene, a member of the glypican family bearing strong similarity to GPC3. (C) 1999 Academic Press.