XVI International Botanical Congess

Acyl-CoA binding proteins (ACBP) are small (10 kDa) cytosolic proteins, which bind long chain acyl-CoAs very strongly. Fatty acids synthesized by the plastid may be exported and converted to acyl-CoAs that are used by the acyltransferases of the endoplasmic reticulum for the synthesis of structural and storage lipids. ACBP genes are constitutively expressed in plants, and ACBPs are present at about 0.1-0.2% of cell protein. The cellular ACBP concentration is approximately 10-40 ?M depending on the estimation of cytosolic volume. Since the protein is present at a relatively high concentration it may well be important in the metabolism of acyl-CoAs. ACP from Brassica napus has been expressed in E. coli and the recombinant protein used to study its potential biological roles using in vitro approaches. These have included fatty acid synthesis by isolated plastids and acyltransferase and fatty acid elongase activities of the endoplasmic reticulum.