Insulin receptor-like protein

Abstract

A receptor for an insulin-like polypeptide is purified from yeast membranes. This "insulin receptor-like protein" has a structure analogous to that of the mammalian insulin receptor. The insulin receptor-like protein of Saccharomyces cerevisiae is a heterotetrameric glycoprotein. The protein has two polypeptide types, a first polypeptide which binds insulin and has an apparent molecular weight of 135,000 to 145,000 daltons and a second polypeptide which has an apparent molecular weight of 90,000 to 95,000 daltons and is phosphorylated on tyrosine in response to binding of insulin by said first polypeptide. The first and second polypeptides are joined by disulfide linkage. The protein requires a divalent metal ion for tyrosine autophosphorylation in response to binding of insulin. The yeast insulin receptor-like protein binds human insulin with a dissociation constant of K.sub.d =8.times.10.sup.-10 M and binds human insulin-like growth factor 1 with a K.sub.d =4.times.10.sup.-10 M.

Dependencies are inferred from the claim text.