Table 1.
Identified phosphorylation sites in MCAK from mammals and Xenopus
| Residue | Human residue | Domain | Kinase | Effect of phosphorylation on in vitro activity | Localization of phosphorylation | In vivo function of phosphorylation | Organism: MCAK/experimental system |
| S92 (Cg)6 | S95 | N-term | Aurora B | Cytoplasm; Kinetochores-asymmetrically distributed over kinetochore pair6 and higher on kinetochores with merotelic attachments.11 | Phosphorylation of S95, S109, S111 inhibits MCAK binding to EB1.26,31 MCAK-S95E, S192E double mutant has reduced depolymerization activity in vivo. MCAK-S95E, S109E, S111E, S115E, S192E (5E) has further reduced activity. MCAK-5E localizes to inner centromeres, while MCAK-5A localizes to kinetochores.6 MCAK-5E also has reduced binding to TIP150.37 |
Hamster/Human cells | |
| T95 (Xl)42 | No effect | G2 phase-Chromosomes Prometaphase-Chromosomes and centromeres/kinetochores |
MCAK-S95A has reduced chromosome arm binding and increased centromeres binding.42 MCAK-4A (S95, S110 (Xl), S166, S192) can reconstitute for wild type MCAK in MT depolymerization in vivo, but not in bipolar spindle assembly.41 |
Xenopus/Xenopus | |||
| S106 6 | S109 | N-term | Aurora B | n.d. | Phosphorylation of S95, S109, S111 inhibits MCAK binding to EB1.26,31 MCAK-S95E, S192E double mutant has reduced depolymerization activity in vivo. MCAK-S95E, S109E, S111E, S115E, S192E (5E) has further reduced activity. MCAK-5E localizes to inner centromeres, while MCAK-5A localizes to kinetochores.6 MCAK-5E also has reduced binding to TIP150.37 |
Hamster/Human cells | |
| 108 6 | S111 | N-term | Aurora B | n.d. | Phosphorylation of S95, S109, S111 inhibits MCAK binding to EB1.26,31 MCAK-S95E, S192E double mutant has reduced depolymerization activity in vivo. MCAK-S95E, S109E, S111E, S115E, S192E (5E) has further reduced activity. MCAK-5E localizes to inner centromeres, while MCAK-5A localizes to kinetochores.6 MCAK-5E also has reduced binding to TIP150.37 |
Hamster/Human cells | |
| S110 41–42 | N.c. | N-term | Aurora B | n.d. | MCAK-S110A has strongly reduced centromere binding.42 MCAK-S110 cannot fully replace wild type MCAK in chromosome alignment.42 MCAK-4A (S95, S110 (Xl), S166, S192) can reconstitute for wild type MCAK in MT depolymerization in vivo, but not in bipolar spindle assembly.41 |
Xenopus/Xenopus | |
| S112 6 | S115 | N-term | Aurora B | n.d. | MCAK-S95E, S192E double mutant has reduced depolymerization activity in vivo. MCAK-S95E, S109E, S111E, S115E, S192E (5E) has further reduced activity. MCAK-5E localizes to inner centromeres, while MCAK-5A localizes to kinetochores.6 MCAK-5E also has reduced binding to TIP150.37 | Hamster/Human cells | |
| S161 10,41 | N.c. | N-term | Aurora B | n.d. | Xenopus/Xenopus | ||
| T162 10 | S152 | N-term | Aurora B | n.d. | Xenopus/Xenopus | ||
| S177 10,41 | S166 | N-term | Aurora B | n.d. | MCAK-4A (S95, S110 (Xl), S166, S192) can reconstitute for wild type MCAK in MT depolymerization in vivo, but not in bipolar spindle assembly.41 | Xenopus/Xenopus | |
|
S19610,41–42 (S186 in Cg)6 |
S192 | Neck | Aurora B | Inhibition | In prometaphase-centromeres and small amount at centrosomes. The phosphorylation is strongly reduced in metaphase. In anaphase/telophase, pS196 (Xl) is observed in the MT midzone. | MCAK-S196A has a stronger affinity for chromosome arms.42 MCAK-S196A can substitute wild type MCAK for spindle assembly, but not for chromosome alignment. MCAK-S196E can not substitute for wild type MCAK in spindle assembly due to decreased MT depolymerization activity.42 MCAK-S95E, S192E double mutant has reduced depolymerization activity in vivo. MCAK-S95E, S109E, S111E, S115E, S192E (5E) has further reduced activity. MCAK-5E localizes to inner centromeres, while MCAK-5A localizes to kinetochores.6 MCAK-5E also has reduced binding to Tip150.37 MCAK-4A (S95, S110 (Xl), S166, S192) can reconstitute for wild type MCAK in MT depolymerization in vivo, but not in bipolar spindle assembly.41 |
Xenopus/Xenopus |
| T229 10 | S225 | Neck | Aurora B | n.d. | Xenopus/Xenopus | ||
| S253 10 | T249 | Neck | Aurora B | n.d. | Xenopus/Xenopus | ||
| S196 43 | S192 | Neck | Aurora A | Inhibition | Xenopus/Xenopus | ||
| S719 43 | S715 | C-term | Aurora A | No effect | MCAK-S719E has reduced binding to aster poles, but increased binding to spindle poles.43 MCAK-S719E has increased activity in promoting spindle bipolarity.43 | Xenopus/Xenopus | |
| T537 44 | Motor domain | CDK1 | Decreased MT depolymerization, but similar ATPase activity. | Spindle and poles | MCAK-T537E has decreased MT depolymerization activity in vivo, but non-phosphorylatable mutants are not more active.44 MCAK-T537A localizes stronger to the centrosomes.44 Both MCAK-T537A and T537E mutants cannot properly rescue MCAK RNAi in chromosome alignment.44 |
Human | |
| S592, S595, S621, S633, S715 45 | C-term | Plk1 | n.d. | MCAK-5E mutants have reduced MT depolymerization activity in vivo.45 MCAK-5E mutants show enhanced intramolecular interactions between N-terminal and C-terminal domains.45 |
Human | ||
| ?? | CaMKIIγ | No effect | CaMKIIγ appears to suppress MCAK activity in vivo, but the mechanism is unknown.46 | Human |
Sites shown in bold are the preferred phosphorylation sites of Aurora B kinase. All amino acid numbers in columns describing function and localization of phosphorylation sites refer to residues in human MCAK, unless stated otherwise. Xl, Xenopus laevis; Cg, Cricetulus griseus; n.d., not determined; n.c., not conserved.