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Sequence analysis and protein import studies of an outer chloroplast envelope polypeptide.

ABSTRACT: A chloroplast outer envelope membrane protein was cloned and sequenced and from the sequence it was possible to deduce a polypeptide of 6.7 kDa. It has only one membrane-spanning region; the C terminus extends into the cytosol, whereas the N terminus is exposed to the space between the two envelope membranes. The protein was synthesized in an in vitro transcription-translation system to study its routing into isolated chloroplasts. The import studies revealed that the 6.7-kDa protein followed a different and heretofore undescribed translocation pathway in the respect that (i) it does not have a cleavable transit sequence, (ii) it does not require ATP hydrolysis for import, and (iii) protease-sensitive components that are responsible for recognition of precursor proteins destined for the inside of the chloroplasts are not involved in routing the 6.7-kDa polypeptide to the outer chloroplast envelope.

SUBMITTER: Salomon M

PROVIDER: S-EPMC54411 | biostudies-other | 1990 Aug

REPOSITORIES: biostudies-other

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Sequence analysis and protein import studies of an outer chloroplast envelope polypeptide.

Salomon M M Fischer K K Flügge U I UI Soll J J

Proceedings of the National Academy of Sciences of the United States of America 19900801 15

A chloroplast outer envelope membrane protein was cloned and sequenced and from the sequence it was possible to deduce a polypeptide of 6.7 kDa. It has only one membrane-spanning region; the C terminus extends into the cytosol, whereas the N terminus is exposed to the space between the two envelope membranes. The protein was synthesized in an in vitro transcription-translation system to study its routing into isolated chloroplasts. The import studies revealed that the 6.7-kDa protein followed a ...[more]

PMID: 2377616

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