Microtubule-associated protein 4 is a protein that in humans is encoded by the MAP4gene.[5]
The protein encoded by this gene is a major non-neuronal microtubule-associated protein. This protein contains a domain similar to the microtubule-binding domains of neuronal microtubule-associated protein (MAP2) and microtubule-associated protein tau (MAPT/TAU). This protein promotes microtubule assembly, and has been shown to counteract destabilization of interphase microtubule catastrophe promotion. Cyclin B was found to interact with this protein, which targets cell division cycle 2 (CDC2) kinase to microtubules. The phosphorylation of this protein affects microtubule properties and cell cycle progression. Multiple alternatively spliced transcript variants encoding distinct isoforms have been observed, the full-length nature of three of which are supported.[6]
uMAP4, the ubiquitous isoform of MAP4, functions in the architecture and positioning of the mitotic spindle in human cells.[7] oMAP4 is predominantly expressed in brain and muscle and has been shown to organise microtubules into antiparallel bundles.[8] mMAP4 is a muscle-specific isoform.[8][9]
^Samora CP, Mogessie B, Conway L, Ross JL, Straube A, McAinsh AD (7 August 2011). "MAP4 and CLASP1 operate as a safety mechanism to maintain a stable spindle position in mitosis". Nature Cell Biology. 13 (9): 1040–1050. doi:10.1038/ncb2297. PMID21822276. S2CID8869880.
^Casey LM, Lyon HD, Olmsted JB (April 2003). "Muscle-specific microtubule-associated protein 4 is expressed early in myogenesis and is not sufficient to induce microtubule reorganization". Cell Motility and the Cytoskeleton. 54 (4): 317–36. doi:10.1002/cm.10105. PMID12601693.
Chapin SJ, Lue CM, Yu MT, Bulinski JC (1995). "Differential expression of alternatively spliced forms of MAP4: a repertoire of structurally different microtubule-binding domains". Biochemistry. 34 (7): 2289–301. doi:10.1021/bi00007a025. PMID7857940.
Bulinski JC, McGraw TE, Gruber D, et al. (1998). "Overexpression of MAP4 inhibits organelle motility and trafficking in vivo". J. Cell Sci. 110. ( Pt 24) (24): 3055–64. doi:10.1242/jcs.110.24.3055. PMID9365275.
Ookata K, Hisanaga S, Sugita M, et al. (1998). "MAP4 is the in vivo substrate for CDC2 kinase in HeLa cells: identification of an M-phase specific and a cell cycle-independent phosphorylation site in MAP4". Biochemistry. 36 (50): 15873–83. doi:10.1021/bi971251w. PMID9398320.
Nguyen HL, Gruber D, Bulinski JC (1999). "Microtubule-associated protein 4 (MAP4) regulates assembly, protomer-polymer partitioning and synthesis of tubulin in cultured cells". J. Cell Sci. 112. ( Pt 12) (12): 1813–24. doi:10.1242/jcs.112.12.1813. PMID10341201.
Chang W, Gruber D, Chari S, et al. (2002). "Phosphorylation of MAP4 affects microtubule properties and cell cycle progression". J. Cell Sci. 114 (Pt 15): 2879–87. doi:10.1242/jcs.114.15.2879. PMID11683421.
Iida J, Itoh TJ, Hotani H, et al. (2002). "The projection domain of MAP4 suppresses the microtubule-bundling activity of the microtubule-binding domain". J. Mol. Biol. 320 (1): 97–106. doi:10.1016/S0022-2836(02)00402-3. PMID12079337.
Mangan ME, Olmsted J (1996). "The gene for microtubule-associated protein 4 (Mtap4) maps to the distal region of mouse chromosome 9". Mamm. Genome. 7 (12): 918–19. doi:10.1007/s003359900270. PMID8995766. S2CID43334937.
