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Characterization of the protein import apparatus in isolated outer envelopes of chloroplasts
Author(s) -
Waegemann Karin,
Soil Jürgen
Publication year - 1991
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/j.1365-313x.1991.00149.x
Subject(s) - biology , bacterial outer membrane , chloroplast , organelle , membrane , biochemistry , vesicle , vesicle associated membrane protein 8 , membrane protein , microbiology and biotechnology , chloroplast membrane , escherichia coli , thylakoid , gene
Summary Isolated outer envelope membrane from pea (Pisum sativum L.) chloroplasts can be used in vitro to study binding and partial translocation of precursor proteins destined for the inside of the organelle. Efficient binding to a receptor protein on the outside of the membrane vesicle and generation of a translocation intermediate depends strictly on the presence of ATP. Protease treatment of the translocation intermediate demonstrates its insertion into the membrane. The membrane‐inserted precursor protein cannot be extracted by 1 M NaCl and is also NaOH resistant to a large extent. Mild solubilization of outer envelope membranes by detergent resulted in the isolation of a complex which still contained the precursor protein. We have identified a constitutively expressed homologue hsc 70 as part of this membrane complex. Antibodies against hsp 70 (inducible heat shock protein 70) were able to immuno‐precipitate the complex bound precursor protein. A second protein of 86 kDa molecular weight (OEP 86) from the outer envelope membrane was also identified as a major component of this complex.