3sf4
From Proteopedia
Crystal structure of the complex between the conserved cell polarity proteins Inscuteable and LGN
Structural highlights
Disease[GPSM2_HUMAN] Autosomal recessive nonsyndromic sensorineural deafness type DFNB;Chudley-McCullough syndrome. Chudley-McCullough syndrome (CMCS) [MIM:604213]: An autosomal recessive neurologic disorder characterized by early-onset sensorineural deafness and specific brain anomalies on MRI, including hypoplasia of the corpus callosum, enlarged cysterna magna with mild focal cerebellar dysplasia, and nodular heterotopia. Some patients have hydrocephalus. Psychomotor development is normal. Note=The disease is caused by mutations affecting the gene represented in this entry.[1] [2] Function[GPSM2_HUMAN] Plays an important role in spindle pole orientation. Interacts and contributes to the functional activity of G(i) alpha proteins. Acts to stabilize the apical complex during neuroblast divisions.[3] [INSC_HUMAN] May function as an adapter linking the Par3 complex to the GPSM1/GPSM2 complex. Involved in spindle orientation during mitosis it may regulate cell proliferation and differentiation in the developing nervous system. May play a role in the asymmetric division of fibroblasts and participate in the process of stratification of the squamous epithelium.[4] Publication Abstract from PubMedInteraction between the mammalian cell polarity proteins mInsc (mammalian homologue of Inscuteable) and Leu-Gly-Asn repeat-enriched protein (LGN), as well as that between their respective Drosophila homologues Inscuteable and Partner of Inscuteable (Pins), plays crucial roles in mitotic spindle orientation, a process contributing to asymmetric cell division. Here, we report a crystal structure of the LGN-binding domain (LBD) of human mInsc complexed with the N-terminal tetratricopeptide repeat (TPR) motifs of human LGN at 2.6-A resolution. In the complex, mInsc-LBD adopts an elongated structure with three binding modules--an alpha-helix, an extended region, and a beta-sheet connected with a loop--that runs antiparallel to LGN along the concave surface of the superhelix formed by the TPRs. Structural analysis and structure-based mutagenesis define residues that are critical for mInsc-LGN association, and reveal that the activator of G-protein signaling 3 (AGS3)-binding protein Frmpd1 [4.1/ezrin/radixin/moesin (FERM) and PSD-95/Dlg/ZO-1 (PDZ) domain-containing protein 1] and its relative Frmpd4 interact with LGN via a region homologous to a part of mInsc-LBD, whereas nuclear mitotic apparatus protein (NuMA) and the C terminus of LGN recognize the TPR domain in a manner different from that by mInsc. mInsc binds to LGN with the highest affinity (K(D) approximately 2.4 nM) and effectively replaces the Frmpd proteins, NuMA, and the LGN C terminus, suggesting the priority of mInsc in binding to LGN. We also demonstrate, using mutant proteins, that mInsc-LGN interaction is vital for stabilization of LGN and for intracellular localization of mInsc. Structural basis for interaction between the conserved cell polarity proteins Inscuteable and Leu-Gly-Asn repeat-enriched protein (LGN).,Yuzawa S, Kamakura S, Iwakiri Y, Hayase J, Sumimoto H Proc Natl Acad Sci U S A. 2011 Nov 29;108(48):19210-5. Epub 2011 Nov 10. PMID:22074847[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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