The Nectin family has at least four members (Nectin-1‑4), all of which show alternate splicing, a transmembrane (TM) region (except for Nectin-1 gamma), and three extracellular Ig-domains. Nectins are highly homologous to the human receptor for poliovirus, and as such, have been alternatively-named poliovirus receptor-related proteins. They do not, however, appear to bind poliovirus. Nectin-3 (also named PRR3, CD113, and PVRL3) is an 83 kDa, type I TM glycoprotein.