Mammalian end binding proteins control persistent microtubule growth.
End binding proteins (EBs) are highly conserved core components of microtubule plus-end tracking protein networks. Here we investigated the roles of the three mammalian EBs in controlling microtubule dynamics and analyzed the domains involved. Protein depletion and rescue experiments showed that EB1 and EB3, but not EB2, promote persistent microtubule growth by suppressing catastrophes. Furthermore, we demonstrated in vitro and in cells that the EB plus-end tracking behavior depends on the calponin homology domain but does not require dimer formation. In contrast, dimerization is necessary for the EB anti-catastrophe activity in cells; this explains why the EB1 dimerization domain, which disrupts native EB dimers, exhibits a dominant-negative effect. When microtubule dynamics is reconstituted with purified tubulin, EBs promote rather than inhibit catastrophes, suggesting that in cells EBs prevent catastrophes by counteracting other microtubule regulators. This probably occurs through their action on microtubule ends, because catastrophe suppression does not require the EB domains needed for binding to known EB partners.
Komarova
Yulia
Y
Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, IL 60611, USA.
De Groot
Christian O
CO
Grigoriev
Ilya
I
Gouveia
Susana Montenegro
SM
Munteanu
E Laura
EL
Schober
Joseph M
JM
Honnappa
Srinivas
S
Buey
Rubén M
RM
Hoogenraad
Casper C
CC
Dogterom
Marileen
M
Borisy
Gary G
GG
Steinmetz
Michel O
MO
Akhmanova
Anna
A
D000818:Animals; D016466:CHO Cells; D002454:Cell Differentiation / Q000502:physiology; D006224:Cricetinae; D003412:Cricetulus; D019281:Dimerization; D006801:Humans; D008869:Microtubule-Associated Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism* / Q000648:ultrastructure; D055503:Protein Multimerization; D017434:Protein Structure, Tertiary
C405804:EB1 microtubule binding proteins; C403664:MAPRE3 protein, human; D008869:Microtubule-Associated Proteins