Plant basic 7 S globulin‐like proteins have insulin and insulin‐like growth factor binding activity

Abstract

Basic 7 S globulin (Bg) is a cysteine‐rich glycoprotein present in soybean seeds. Mature Bg is composed of high‐ and low‐kDa subunits linked by disulfide bonding. A ligand blotting experiment using [¹²⁵I]insulin and [¹²⁵I]insulin‐like growth factor‐I and ‐II showed that Bg subunits are able to bind not only to insulin but to insulin‐like growth factors‐I and ‐II. Bg‐like proteins from other legume species cross‐reacted with anti‐Bg antibody also bind to insulin and insulin‐like growth factors. Bg‐like protein in carrot cells was found to have insulin binding activity. Bg‐like proteins may be involved in an insulin‐like regulatory mechanism in many plant species.