A VIEW ABOUT THE FUNCTION OF AUXIN-BINDING PROTEINS AT PLASMA-MEMBRANES

The auxin-binding protein isolated from maize coleoptiles and characterized in detail describes an auxin recognition protein at the outer surface of the plasmalemma which mediates the auxin effect on cell elongation in maize coleoptiles. Its homologue in tobacco mesophyll protoplasts mediates the auxin effect on secretion. The cDNA clones of the auxin-binding protein independently sequenced in three different laboratories contain one unique open reading frame describing the auxin-binding protein as a nonmembrane-integrated glycoprotein containing the ER-sorting C-terminal tetrapeptide KDEL. There are hints but no hard facts that a membrane-located receptor for the ABP-auxin complex and a G-protein may be included in this signal-transducing pathway. © 1990 Kluwer Academic Publishers.