Auxin binding-protein1 (ABP1), a receptor to regulate auxin transport and early auxin genes in an interlocking system with PIN proteins and the receptor TIR1.

Compared to the past 10 years, a flurry of publications, reviews, and experimental papers on ABP1 appeared in the last couple of years. Certainly, the reason is that new methods and conceptual approaches appeared to tackle the questions posed by this enigmatic auxin-binding protein. Part of the enigma is the obvious central importance of ABP1, documented by the embryo-lethal property of the homozygous T-DNA insertion into this gene1. At the same time, this very property hindered progress in studying ABP1. Another delaying influence on ABP1 research was the fact that regulation of early auxin genes was fully explained by the mechanism provided by TRI1, the second auxin receptor2-4.