Isolation of a putative receptor fromZea maysmicrosomal membranes that interacts with the G-protein, GPα1

Abstract
The C‐terminal region of a heterotrimeric G‐protein α‐subunit is known to be one of the principal determinants governing its interaction with its cognate receptor. Use of an oligopeptide corresponding to the fifteen C‐terminal residues of the Arabidopsis Gα‐subunit (GPα1), as an affinity ligand, led to the resolution of a tightly binding 37 kDa membrane polypeptide from detergent solubilised Zea microsomal fraction membranes. An identical polypeptide bound tightly to an affinity matrix containing recombinant GPα1 protein as ligand: binding and release of this 37 kDa protein was dependent on the activation state of GPα1 which was regulated by inclusion or omission of the G‐protein activator AlF 4. Finally, the isolated 37 kDa protein was labelled with the lectin concanavalin A, indicating it to be glycosylated. These data are consistent with the identity of the 37 kDa membrane polypeptide as a receptor that interacts with the Zea homologue of GPα1.