Tau binds to microtubule through the C-terminal repeat domain and 4R bind more tightly than 3R, while phosphorylation, especially of the repeat domain tends to decrease binding.
A further potent detaching site is phosphoS214, which can be phosphorylated by PKA and other kinases of the AGC group (PKA/PKG/PKC group of protein kinases), and is up-regulated during mitosis (16, 63). Tau contains one or two cysteines in the repeat domain (C291 in R2, present in 4R isoforms, and C322 in R3), which can be engaged in intra- or intermolecular cross-linking affecting conformation, dimerization and aggregation (108).
Two hexapeptide motifs at the beginning of R2 and R3 promote paired helical filament (PHF) aggregation by inducing β-structure.
Tyrosine kinases target Y18 [fyn, (79)] and Y394 [abl, (31)].
The lysine-isoleucine-glycineserine motif (KIGS) or lysine-cysteineglycine-serine motif (KCGS) motifs in the repeat domain (S262, S293, S324, S356) can be phosphorylated by MARK, PKA, SAD kinases, CaMKII and p70S6K, which strongly reduces the tau microtubule interactions (36, 74, 96), [note that phosphorylation at these sites also inhibits tau aggregation, illustrating an analogous role for the repeat domain in the physiological and pathological functions of tau (106)].
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If you find BEL Commons useful in your work, please consider citing: Hoyt, C. T., Domingo-Fernández, D., & Hofmann-Apitius, M. (2018). BEL Commons: an environment for exploration and analysis of networks encoded in Biological Expression Language. Database, 2018(3), 1–11.