A RECEPTOR COMPONENT OF THE CHLOROPLAST PROTEIN TRANSLOCATION MACHINERY

The chloroplast outer envelope protein OEP86 functions as a receptor i n precursor protein translocation into chloroplasts. Sequence analysis suggests that the precursor of OEP86 is directed to the chloroplast o uter envelope by a cleavable, negatively charged, and unusually long a mino-terminal peptide. This presequence is unlike other potential targ eting signals and suggests the existence of another membrane insertion pathway. insertion of precursor OEP86 required the hydrolysis of aden osine triphosphate and the existence of surface exposed chloroplast me mbrane components, and it was not competed by another precursor protei n destined for the internal plastid compartments.