Wu H, Reissner C, Kuhlendahl S, Coblentz B, Reuver S, Kindler S, Gundelfinger E D, Garner C C
University of Alabama at Birmingham, Department of Neurobiology, 1719 Sixth Avenue South CIRC 589, Birmingham, AL 35294-0021, USA.
EMBO J. 2000 Nov 1;19(21):5740-51. doi: 10.1093/emboj/19.21.5740.
Membrane-associated guanylate kinase homologs (MAGUKs) are multidomain proteins found to be central organizers of cellular junctions. In this study, we examined the molecular mechanisms that regulate the interaction of the MAGUK SAP97 with its GUK domain binding partner GKAP (GUK-associated protein). The GKAP-GUK interaction is regulated by a series of intramolecular interactions. Specifically, the association of the Src homology 3 (SH3) domain and sequences situated between the SH3 and GUK domains with the GUK domain was found to interfere with GKAP binding. In contrast, N-terminal sequences that precede the first PDZ domain in SAP97, facilitated GKAP binding via its association with the SH3 domain. Utilizing crystal structure data available for PDZ, SH3 and GUK domains, molecular models of SAP97 were generated. These models revealed that SAP97 can exist in a compact U-shaped conformation in which the N-terminal domain folds back and interacts with the SH3 and GUK domains. These models support the biochemical data and provide new insights into how intramolecular interactions may regulate the association of SAP97 with its binding partners.
膜相关鸟苷酸激酶同源物（MAGUKs）是多结构域蛋白，被发现是细胞连接的核心组织者。在本研究中，我们研究了调节MAGUK SAP97与其鸟苷酸激酶（GUK）结构域结合伴侣GKAP（GUK相关蛋白）相互作用的分子机制。GKAP与GUK的相互作用受一系列分子内相互作用的调节。具体而言，发现Src同源3（SH3）结构域以及位于SH3和GUK结构域之间的序列与GUK结构域的结合会干扰GKAP的结合。相反，SAP97中第一个PDZ结构域之前的N端序列通过与SH3结构域的结合促进了GKAP的结合。利用可获得的PDZ、SH3和GUK结构域的晶体结构数据，生成了SAP97的分子模型。这些模型表明，SAP97可以以紧凑的U形构象存在，其中N端结构域向后折叠并与SH3和GUK结构域相互作用。这些模型支持了生化数据，并为分子内相互作用如何调节SAP97与其结合伴侣的关联提供了新的见解。
