Download MendeleyX-ray structure of a protein-conducting channel
van den Berg, B., Clemons Jr., W.M., Collinson, I., Modis, Y., Hartmann, E., Harrison, S.C., Rapoport, T.A.(2004) Nature 427: 36-44
- PubMed: 14661030
- DOI: https://doi.org/10.1038/nature02218
- Primary Citation of Related Structures:
1RH5, 1RHZ - PubMed Abstract:
A conserved heterotrimeric membrane protein complex, the Sec61 or SecY complex, forms a protein-conducting channel, allowing polypeptides to be transferred across or integrated into membranes. We report the crystal structure of the complex from Methanococcus jannaschii at a resolution of 3.2 A. The structure suggests that one copy of the heterotrimer serves as a functional translocation channel. The alpha-subunit has two linked halves, transmembrane segments 1-5 and 6-10, clamped together by the gamma-subunit. A cytoplasmic funnel leading into the channel is plugged by a short helix. Plug displacement can open the channel into an 'hourglass' with a ring of hydrophobic residues at its constriction. This ring may form a seal around the translocating polypeptide, hindering the permeation of other molecules. The structure also suggests mechanisms for signal-sequence recognition and for the lateral exit of transmembrane segments of nascent membrane proteins into lipid, and indicates binding sites for partners that provide the driving force for translocation.
- Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, Massachusetts 02115, USA.
Organizational Affiliation:
