Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.6.4.4 (kinesin)
 5,033 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Reorganization of the cortical cytoskeleton is a hallmark of T lymphocyte activation. Upon binding to antigen presenting cells, the T cells rapidly undergo cytoskeletal re-organization thus forming a cap at the cell-cell contact site leading to receptor clustering, protein segregation, and cellular polarization. Previously, we reported cloning of the human lymphocyte homologue of the Drosophila Discs Large tumor suppressor protein (hDlg). Here we show that a novel protein termed GAKIN binds to the guanylate kinase-like domain of hDlg. Affinity protein purification, peptide sequencing, and cloning of GAKIN cDNA from Jurkat J77 lymphocytes identified GAKIN as a novel member of the kinesin superfamily of motor proteins. GAKIN mRNA is ubiquitously expressed, and the predicted amino acid sequence shares significant sequence similarity with the Drosophila kinesin-73 motor protein. GAKIN sequence contains a motor domain at the NH(2) terminus, a central stalk domain, and a putative microtubule-interacting sequence called the CAP-Gly domain at the COOH terminus. Among the MAGUK superfamily of proteins examined, GAKIN binds to the guanylate kinase-like domain of PSD-95 but not of p55. The hDlg and GAKIN are localized mainly in the cytoplasm of resting T lymphocytes, however, upon CD2 receptor cross-linking the hDlg can translocate to the lymphocyte cap. We propose that the GAKIN-hDlg interaction lays the foundation for a general paradigm of coupling MAGUKs to the microtubule-based cytoskeleton, and that this interaction may be functionally important for the intracellular trafficking of MAGUKs and associated protein complexes in vivo.
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PMID:GAKIN, a novel kinesin-like protein associates with the human homologue of the Drosophila discs large tumor suppressor in T lymphocytes. 1085 2

Membrane-associated guanylate kinase homologues (MAGUKs) are generally found under the plasma membrane of cell-cell contact sites and function as scaffolding proteins by linking cytoskeletal and signaling molecules to transmembrane receptors. The correct targeting of MAGUKs is essential for their receptor-clustering function; however, the molecular mechanism of their intracellular transport is unknown. Here, we show that the guanylate kinase-like domain of human discs large protein binds directly within the amino acids 607-831 of the stalk domain of GAKIN, a kinesin-like protein of broad distribution. The primary structure of the binding segment, termed MAGUK binding stalk domain, is conserved in Drosophila kinesin-73 and some other motor and non-motor proteins. This stalk segment is not found in GKAP, a synaptic protein that interacts with the guanylate kinase-like domain, and unlike GKAP, the binding of GAKIN is not regulated by the intramolecular interactions within the discs large protein. The recombinant motor domain of GAKIN is an active microtubule-stimulated ATPase with k(cat) = 45 s(-1), K(0.5 (MT)) = 0.1 microm. Overexpression of green fluorescent protein-fused GAKIN in Madin-Darby canine kidney epithelial cells induced long projections with both GAKIN and endogenous discs large accumulating at the tip of these projections. Importantly, the accumulation of endogenous discs large was eliminated when a mutant GAKIN lacking its motor domain was overexpressed under similar conditions. Taken together, our results indicate that discs large is a cargo molecule of GAKIN and suggest a mechanism for intracellular trafficking of MAGUK-laden vesicles to specialized membrane sites in mammalian cells.
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PMID:Direct interaction with a kinesin-related motor mediates transport of mammalian discs large tumor suppressor homologue in epithelial cells. 1249 41

Phosphatidylinositol-(3,4,5)-trisphosphate (PIP3), a product of phosphatidylinositol 3-kinase, is an important second messenger implicated in signal transduction and membrane transport. In hippocampal neurons, the accumulation of PIP3 at the tip of neurite initiates the axon specification and neuronal polarity formation. We show that guanylate kinase-associated kinesin (GAKIN), a kinesin-like motor protein, directly interacts with a PIP3-interacting protein, PIP3BP, and mediates the transport of PIP3-containing vesicles. Recombinant GAKIN and PIP3BP form a complex on synthetic liposomes containing PIP3 and support the motility of the liposomes along microtubules in vitro. In PC12 cells and cultured hippocampal neurons, transport activity of GAKIN contributes to the accumulation of PIP3 at the tip of neurites. In hippocampal neurons, altered accumulation of PIP3 by overexpression of GAKIN constructs led to the loss of the axonally differentiated neurites. Together, these results suggest that, in neurons, the GAKIN-PIP3BP complex transports PIP3 to the neurite ends and regulates neuronal polarity formation.
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PMID:Transport of PIP3 by GAKIN, a kinesin-3 family protein, regulates neuronal cell polarity. 1686 56

Cytokinesis is the final step of cell division that completes the separation of two daughter cells. We found that the human discs large (hDlg) tumor suppressor homologue is functionally involved in cytokinesis. The guanylate kinase (GUK) domain of hDlg mediates the localization of hDlg to the midbody during cytokinesis, and over-expression of the GUK domain in U2OS and HeLa cells impaired cytokinesis. Mouse embryonic fibroblasts (MEFs) derived from dlg mutant mice contained an increased number of multinucleated cells and showed reduced proliferation in culture. A kinesin-like motor protein, GAKIN, which binds directly to the GUK domain of hDlg, exhibited a similar intracellular distribution pattern with hDlg throughout mitosis and localized to the midbody during cytokinesis. However, the targeting of hDlg and GAKIN to the midbody appeared to be independent of each other. The midbody localization of GAKIN required its functional kinesin-motor domain. Treatment of cells with the siRNA specific for hDlg and GAKIN caused formation of multinucleated cells and delayed cytokinesis. Together, these results suggest that hDlg and GAKIN play functional roles in the maintenance of midbody architecture during cytokinesis.
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PMID:Functional involvement of human discs large tumor suppressor in cytokinesis. 1876 Feb 73

The membrane-associated guanylate kinase (MAGUK) scaffold proteins share a signature guanylate kinase (GK) domain. Despite their diverse functional roles in cell polarity control and synaptic signaling, the currently known mode of action of MAGUK GK is via its binding to phosphorylated short peptides from target proteins. Here, we discover that the GK domain of DLG MAGUK binds to an unphosphorylated and autonomously folded domain within the stalk region (MAGUK binding stalk [MBS] domain) of a kinesin motor KIF13B with high specificity and affinity. The structure of DLG4 GK in complex with KIF13B MBS reveals the molecular mechanism governing this atypical GK/target recognition mode and provides insights into DLG/KIF13B complex-mediated regulation of diverse cellular processes such as asymmetric cell division. We further show that binding to non-phosphorylated targets is another general property of MAGUK GKs, thus expanding the mechanisms of action of the MAGUK family proteins.
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PMID:An Atypical MAGUK GK Target Recognition Mode Revealed by the Interaction between DLG and KIF13B. 2764 59