1RH5

The structure of a protein conducting channel

Summary for 1RH5

• Entry DOI: 10.2210/pdb1rh5/pdb
• Related: 1RHZ
• Descriptor: Preprotein translocase secY subunit, Preprotein translocase secE subunit, SecBeta (3 entities in total)
• Functional Keywords: protein translocation, secy, membrane protein, protein channels, protein transport
• Biological source: Methanocaldococcus jannaschii; More
• Cellular location: Cell membrane; Multi-pass membrane protein: Q60175; Cell membrane; Single-pass membrane protein: Q57817
• Total number of polymer chains: 3
• Total formula weight: 61931.03

Authors

van den Berg, B.,Clemons Jr., W.M.,Collinson, I.,Modis, Y.,Hartmann, E.,Harrison, S.C.,Rapoport, T.A. (deposition date: 2003-11-13, release date: 2004-01-06, Last modification date: 2024-02-14)

Primary citation

van den Berg, B.,Clemons Jr., W.M.,Collinson, I.,Modis, Y.,Hartmann, E.,Harrison, S.C.,Rapoport, T.A.
X-ray structure of a protein-conducting channel
Nature, 427:36-44, 2004

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.

PubMed: 14661030
DOI: 10.1038/nature02218

Experimental method

X-RAY DIFFRACTION (3.2 Å)