GPR98: Proteins and Enzymes

GPR98, also known as Very Large G Protein-Coupled Receptor-1 (VLGR1), is an Orphan-A GPCR with an unknown ligand. VLGR1 consists of three expressed isoforms. VLGR1 has a large ectodomain containing multiple CALX-beta repeats that resemble regulatory domains of sodium-calcium exchanger proteins. VLGR1b, which is the only form expressed in mouse, is apparently the largest known cell-surface protein with an ectodomain containing 35 CALX- repeats and a pentraxin homology domain. The MASS1 gene, which is a fragment of the very large G-protein-coupled receptor VLGR1, is mutated in the Frings mouse model of audiogenic epilepsy. VLGR1 has been reported to be widely expressed in normal solid tissues. ESTs have been isolated from human adrenal, brain, colon, eye, kidney, nerve, and testis libraries.