Signalling Elements in Higher Plants: Identification and Molecular Analysis of an Auxin-Binding Protein, GTP-Binding Regulatory Proteins and Calcium Sensitive Proteins

In eucaryotic cells external signals detected by receptors are translated into a limited repertoire of intracellular second messengers. Occupancy of these receptors initiates the production of active messengers, including the well studied cyclic adenosine monophosphate (cAMP) as well as the recently discovered messenger molecules that are derived from phosphoinositides such as arachidonic acid, inositol-l,4,5-triphosphate, and 1,2-diacylglycerol (for review see: Berridge 1986; Newton and Brown 1986; Boss and Morre 1989). These messengers are capable of regulating a vast array of physiological and biochemical processes either by direct interaction with distinct proteins or indirectly by activating enzymes which trigger conformational changes in the final target proteins. However, the number of second messengers in eucaryotic cells appears to be surprisingly small, indicating that most probably only a limited number of internal signal pathways are needed, albeit remarkably universally in all eucaryotes analyzed up to now, to transduce these signals to their final biological destination.