Expression of normal and mutagenized apolipoprotein CII in procaryotic cells. Structure-function relationship.

Abstract

A full-length human apo CII cDNA clone has been constructed by completing the 5' end of an incomplete cDNA with a 44 bp long synthetic oligonucleotide. This apo CII cDNA insert was cloned into the pSP19 expression vector and transcribed and translated in vitro. Its N-terminal signal sequence (23 amino-acid residues) was accurately cleaved during cotranslational translocation through endoplasmic reticulum membranes to yield the mature apo CII. Mature apo CII was expressed on a preparative scale as fusion protein apo CII-beta-galactosidase with the full-length apo CII cDNA integrated into the pUR291 vector. Furthermore it was expressed in E. coli transformed with the pKK233-2 apo CII clone. The preform was accurately processed by the host cell. C-Terminal apo CII deletion mutants generated by partial Bal31 digestion of the pKK233-2 apo CII vector yielded well-defined truncated apo CII polypeptides on a preparative scale which allowed the determination of the polypeptide domain responsible for the activation of the serum lipoprotein lipase.