Engelsk definition
A heterodimeric protein that is a cell surface antigen associated with lymphocyte activation. The initial characterization of this protein revealed one identifiable heavy chain (FUSION REGULATORY PROTEIN 1, HEAVY CHAIN) and an indeterminate smaller light chain. It is now known that a variety of light chain subunits (FUSION REGULATORY PROTEIN 1, LIGHT CHAINS) can dimerize with the heavy chain. Depending upon its light chain composition a diverse array of functions can be found for this protein. Functions include: type L amino acid transport, type y+L amino acid transport and regulation of cellular fusion.