3bg1
From Proteopedia
Architecture of a Coat for the Nuclear Pore Membrane
Structural highlights
Function[SEC13_HUMAN] Functions as a component of the nuclear pore complex (NPC) and the COPII coat. At the endoplasmic reticulum, SEC13 is involved in the biogenesis of COPII-coated vesicles.[1] [NU145_YEAST] Functions as a component of the nuclear pore complex (NPC). NPC components, collectively referred to as nucleoporins (NUPs), can play the role of both NPC structural components and of docking or interaction partners for transiently associated nuclear transport factors. Active directional transport is assured by both, a Phe-Gly (FG) repeat affinity gradient for these transport factors across the NPC and a transport cofactor concentration gradient across the nuclear envelope (GSP1 and GSP2 GTPases associated predominantly with GTP in the nucleus, with GDP in the cytoplasm). NUP145 is autocatalytically cleaved in vivo in 2 polypeptides which assume different functions in the NPC. NUP145N as one of the FG repeat nucleoporins participates in karyopherin interactions and contains part of the autocatalytic cleavage activity. NUP145C as part of the NUP84 complex is involved in nuclear poly(A)+ RNA and tRNA export. It is also required for normal NPC distribution (probably through interactions with MLP1 and MLP2) and NPC assembly, as well as for normal nuclear envelope organization.[2] [3] [4] [5] [6] [7] [8] [9] [10] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe symmetric core of the nuclear pore complex can be considered schematically as a series of concentric cylinders. A peripheral cylinder coating the pore membrane contains the previously characterized, elongated heptamer that harbors Sec13-Nup145C in its middle section. Strikingly, Sec13-Nup145C crystallizes as a hetero-octamer in two space groups. Oligomerization of Sec13-Nup145C was confirmed biochemically. Importantly, the numerous interacting surfaces in the hetero-octamer are evolutionarily highly conserved, further underlining the physiological relevance of the oligomerization. The hetero-octamer forms a slightly curved, yet rigid rod of sufficient length to span the entire height of the proposed membrane-adjacent cylinder. In concordance with the dimensions and symmetry of the nuclear pore complex core, we suggest that the cylinder is constructed of four antiparallel rings, each ring being composed of eight heptamers arranged in a head-to-tail fashion. Our model proposes that the hetero-octamer would vertically traverse and connect the four stacked rings. Architecture of a coat for the nuclear pore membrane.,Hsia KC, Stavropoulos P, Blobel G, Hoelz A Cell. 2007 Dec 28;131(7):1313-26. PMID:18160040[11] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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