Formation of Auxin-bound Proteins

Abstract

THE occurrence of auxin–protein complexes has been recognized for a long time, but very little is known about the mechanism of the binding process. According to Siegel and Galston¹ energy for the coupling of auxin to protein is supplied by adenosine triphosphate, and the process can be inhibited by several metabolic inhibitors. Galston et al.^2,3 have observed, using indole-3-acetic acid (IAA) labelled with carbon-14, that auxin is not bound appreciably to any of the cell organelles but that the particle-free supernatant contains macro-molecules to which auxin is bound. Masuda⁴ has recently put forward the suggestion that IAA may render ribonucleic acid (RNA) separate from ribonucleoprotein by becoming complexed with the protein moiety. During the course of an investigation on the binding of auxin to protein in growing tissues it was observed that several amino-acids stimulated the binding process. This communication summarizes some of the observations made concerning the inter-relationship between the binding process and protein synthesis.