Information for targeting to the chloroplastic inner envelope membrane is contained in the mature region of the maize Bt1-encoded protein
- Univ. of Wisconsin, Madison, WI (United States)
Based on the protein sequence deduced from a cDNA clone, it has been proposed that the maize Bt1 locus encodes an amyloplast membrane metabolite translocator protein. The present work provides further evidence for this hypothesis by showing that the gene product of Bt1 could be imported into chloroplasts in vitro and processed to lower molecular weight mature proteins. More importantly, the imported mature proteins were localized to the inner envelope membrane, where metabolite tranlocators are located in plastids. In addition, the location of information for targeting to the inner membrane was investigated by constructing and analyzing the import of chimeric precursor proteins. A chimeric protein with the transit peptide of the precursor to the small subunit of ribulose-1,5-bisphosphate carboxylase fused to the mature region of the Bt1-encoded protein was targeted to the inner envelope membrane of chloroplasts. Moreover, a chimeric protein with the transit peptide of the Bt1-encoded protein fused to the mature protein of the light-harvesting chlorophyll a/b binding protein was targeted to the thylakoid. These results indicate that the transit peptide of the Bt1-encoded protein functions primarily as a stromal targeting sequence. The information for targeting to the chloroplastic inner envelope membrane is contained in the mature region of the protein.
- DOE Contract Number:
- FG02-86ER13526
- OSTI ID:
- 136717
- Journal Information:
- Journal of Biological Chemistry, Vol. 267, Issue 26; Other Information: PBD: 15 Sep 1992
- Country of Publication:
- United States
- Language:
- English
Similar Records
Role of transit peptides in the localization of chloroplastic proteins
Structure and expression of a pea nuclear gene encoding a chlorophyll a/b-binding polypeptide