In vitro processing of tropoelastin: investigation of a possible transport function associated with the carboxy-terminal domain.

In vitro translation systems were used to characterize the processing of bovine tropoelastin isoforms and to investigate the possibility that the carboxy-terminal 19 amino acids of tropoelastin encode a molecular domain that directs intracellular transport. Immunoprecipitation with domain-specific antibodies demonstrated that multiple tropoelastin isoforms corresponding to those identified in tissue and cell culture studies were correctly translated and were processed by dog pancreas microsomes. Our results demonstrate that all tropoelastin isoforms are translocated completely into the microsomal vesicle and do not remain associated with the microsomal membrane. These results exclude the possibility that the carboxy-terminal domain of tropoelastin functions as a trafficking signal by effecting an association between tropoelastin and an intracellular membraneous compartment.