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Structure of yeast importin a bound to the membrane protein Nuclear Localization Signal sequence of INM protein Heh2
Structural highlights
FunctionIMA1_YEAST Binds specifically and directly to substrates containing either a simple or bipartite NLS motif. Promotes docking of import substrates to the nuclear envelope. Seems to act as a cytosolic receptor for both simple and bipartite NLS motifs (By similarity).[1] [2] [3] Publication Abstract from PubMedTargeting of ER-synthesized membrane proteins to the inner nuclear membrane (INM) has long been explained by the diffusion-retention model. However, several INM proteins contain non-classical nuclear localization signal (NLS) sequences, which, in a few instances, have been shown to promote importin alpha/beta- and Ran-dependent translocation to the INM. Here, using structural and biochemical methods, we show that yeast INM proteins Heh2 and Src1/Heh1 contain bipartite import sequences that associate intimately with the minor NLS-binding pocket of yeast importin alpha and unlike classical NLSs efficiently displace the IBB domain in the absence of importin beta. In vivo, the intimate interactions at the minor NLS-binding pocket make the h2NLS highly efficient at recruiting importin alpha at the ER and drive INM localization of endogenous Heh2. Thus, h1/h2NLSs delineate a novel class of super-potent, IBB-like membrane protein NLSs, distinct from classical NLSs found in soluble cargos and of general interest in biology. Distinctive Properties of the Nuclear Localization Signals of Inner Nuclear Membrane Proteins Heh1 and Heh2.,Lokareddy RK, Hapsari RA, van Rheenen M, Pumroy RA, Bhardwaj A, Steen A, Veenhoff LM, Cingolani G Structure. 2015 May 19. pii: S0969-2126(15)00175-6. doi:, 10.1016/j.str.2015.04.017. PMID:26051712[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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