GLYCOSYLATION OF VIP RECEPTORS - A MOLECULAR-BASIS FOR RECEPTOR HETEROGENEITY

Apparent molecular weights of VIP-binding proteins differ greatly acco rding to species and to tissue. In this study, we used plasma membrane s from various species (human, rat, pig) and tissues (melanoma, intest ine, liver), which display major I-125-VIP-labeled components with mol ecular weights ranging from M, = 51,800 to 66,800. With the exception of porcine receptor, the various VIP receptors had similar apparent mo lecular weights after removal of their N-linked carbohydrates. In addi tion to differences in the amount of asparagine-linked glycans, our re sults also revealed differences in the composition of the oligosacchar ide chains, which can also account for the heterogeneity in the molecu lar weights of the VIP receptor.