Chapter One - Cell and Molecular Biology of Microtubule Plus End Tracking Proteins: End Binding Proteins and Their Partners
Introduction
The cytoskeleton is a scaffold made of proteinaceous fibers that is required for the majority of essential cellular functions, such as maintenance of cellular shape, cell motility, intracellular transport, and cell division. It is a complex and often highly dynamic structure composed of several major components. One of them are microtubules (MTs), which are among the most ubiquitous cytoskeletal elements present in all eukaryotic cells. MTs are hollow asymmetric tubes that are built and broken down from their ends. In this review, we zoom in on a tiny part of the MT—its growing end. This structure, which is 25 nm in diameter and not more than 1 or 2 μm in length, is surprisingly complex: it concentrates a large set of structurally diverse proteins and serves as a site of convergence of numerous cellular processes. Here, we summarize what is known about a peculiar and highly conserved group of proteins that form comet-like accumulations at the growing MT tips, discuss the molecular mechanisms of MT plus end localization, and describe how MT end localization relates to the functions of these proteins.
Section snippets
Tubulin
MTs are cylindrical protein filaments found in all eukaryotes. The structural subunit of MTs is tubulin, a heterodimeric protein composed of two polypeptide chains designated α and β tubulin (Krauhs et al., 1981, Ponstingl et al., 1981). The α and β monomers have similar masses of ~ 55 kDa and interact noncovalently to form a very stable heterodimer, the functional form of the protein (Wade, 2009). Individual tubulin heterodimers are 8 nm in length. Each tubulin monomer can be divided into three
MT Regulators
MTs are primarily controlled by factors that can directly regulate different parameters of MT polymerization dynamics, sever or bundle existing MTs or affect MTs indirectly, through influencing other proteins (Lyle et al., 2009a, Lyle et al., 2009b). MTs can be stabilized in several ways: by preventing catastrophes, by rescuing depolymerizing MTs, or by decreasing shrinkage velocity. MT regulators that induce catastrophes, prevent rescues, or increase shrinkage speeds destabilize MTs (Desai &
MT Plus End Tracking Proteins (+TIPs)
MT plus end tracking proteins (+ TIPs) belong to a distinct class of MAPs that accumulate at the growing MT plus ends (Schuyler and Pellman, 2001). Their MT end localization is the distinguishing feature when compared to other MAPs. Most + TIPs associate preferentially with growing and not depolymerizing MT ends. Interestingly, some + TIPs are also able to track shrinking MT ends (“backtracking”). This phenomenon is characteristic for + TIPs from budding yeast (Carvalho et al., 2004, Salmon, 2005),
+ TIP Families
Since the discovery of the first + TIP, CLIP-170 (Perez et al., 1999) multiple proteins showing this behavior have been identified. Importantly, some + TIPs localize in a comet-like pattern at MT ends: they are highly concentrated at or close to the freshly polymerized MT tip, while their accumulation decreases exponentially on the older MT lattice. In mammalian cells, such + TIP comets are typically 1–2 μm in length. Since 1 μm of a 13-protofilament MT contains ~ 1600 tubulin dimers, hundreds of +
Conclusions and Future Directions
+ TIPs have emerged as important MT regulators and consequently as key factors in a wide range of vital cellular processes. What started by observation of a peculiar dynamic behavior, quickly put + TIPs in the spotlight. The field made remarkable progress, not just in the discovery of a notably large number of new + TIPs but also in understanding the mechanisms of their action and their interactions with MTs and other + TIPs.
It is clear that EB family proteins form the core of the comet-making + TIP
Acknowledgments
We thank Babet van der Vaart for critically reading the chapter. This work was supported by the Netherlands Organization for Scientific Research grants ALW-VICI and ZonMW-TOP to A.A. and by Fundação para a Ciência e a Tecnologia fellowship to S.M.G.
References (446)
- et al.
Clasps are CLIP-115 and -170 associating proteins involved in the regional regulation of microtubule dynamics in motile fibroblasts
Cell
(2001) - et al.
Aurora B regulates MCAK at the mitotic centromere
Dev. Cell
(2004) - et al.
CDC2 phosphorylation of the fission yeast dis1 ensures accurate chromosome segregation
Curr. Biol.
(2006) - et al.
CLIP-170/tubulin-curved oligomers coassemble at microtubule ends and promote rescues
Curr. Biol.
(2004) - et al.
Mitotic regulation of the stability of microtubule plus-end tracking protein EB3 by ubiquitin ligase SIAH-1 and Aurora mitotic kinases
J. Biol. Chem.
(2009) - et al.
The role of the proteins Kar9 and Myo2 in orienting the mitotic spindle of budding yeast
Curr. Biol.
(2000) - et al.
Kinetic analysis of tubulin assembly in the presence of the microtubule-associated protein TOGp
J. Biol. Chem.
(2007) - et al.
Context-specific requirements of functional domains of the Spectraplakin Short stop in vivo
Mech. Dev.
(2009) - et al.
The multipurpose 15-protofilament microtubules in C. elegans have specific roles in mechanosensation
Curr. Biol.
(2009) - et al.
Stabilization of overlapping microtubules by fission yeast CLASP
Dev. Cell
(2007)
XMAP215 is a processive microtubule polymerase
Cell
The EB1 homolog Mal3 stimulates the ATPase of the kinesin Tea2 by recruiting it to the microtubule
J. Biol. Chem.
CLIP170-like tip1p spatially organizes microtubular dynamics in fission yeast
Cell
Characterization of functional domains of human EB1 family proteins
J. Biol. Chem.
The microtubule plus end-tracking proteins mal3p and tip1p cooperate for cell-end targeting of interphase microtubules
Curr. Biol.
Tea2p kinesin is involved in spatial microtubule organization by transporting tip1p on microtubules
Dev. Cell
Cell cycle control of kinesin-mediated transport of Bik1 (CLIP-170) regulates microtubule stability and dynein activation
Dev. Cell
Microtubule assembly: lattice GTP to the rescue
Curr. Biol.
The CENP-F-like proteins HCP-1 and HCP-2 target CLASP to kinetochores to mediate chromosome segregation
Curr. Biol.
SNIP, a novel SNAP-25-interacting protein implicated in regulated exocytosis
J. Biol. Chem.
Cloning of three novel neuronal Cdk5 activator binding proteins
Gene
TOR signaling regulates microtubule structure and function
Curr. Biol.
New data on the microtubule surface lattice
Biol. Cell
ATPase cycle of the nonmotile kinesin NOD allows microtubule end tracking and drives chromosome movement
Cell
Pore membrane and/or filament interacting like protein 1 (POMFIL1) is predominantly expressed in the nervous system and encodes different protein isoforms
Gene
Asymmetric microtubule pushing forces in nuclear centering
Curr. Biol.
The minus end in sight
Curr. Biol.
CLIP-115, a novel brain-specific cytoplasmic linker protein, mediates the localization of dendritic lamellar bodies
Neuron
Kin I kinesins are microtubule-destabilizing enzymes
Cell
ch-TOGp is required for microtubule aster formation in a mammalian mitotic extract
J. Biol. Chem.
Regulation of dynactin through the differential expression of p150Glued isoforms
J. Biol. Chem.
Role of CLASP2 in microtubule stabilization and the regulation of persistent motility
Curr. Biol.
Disease-associated mutations in the p150(Glued) subunit destabilize the CAP-gly domain
Biochemistry
Tracking the ends: a dynamic protein network controls the fate of microtubule tips
Nat. Rev. Mol. Cell Biol.
The microtubule plus-end-tracking protein CLIP-170 associates with the spermatid manchette and is essential for spermatogenesis
Genes Dev.
Stu2p binds tubulin and undergoes an open-to-closed conformational change
J. Cell Biol.
The kinesin ATK5 functions in early spindle assembly in Arabidopsis
Plant Cell
CLASP modulates microtubule-cortex interaction during self-organization of acentrosomal microtubules
Mol. Biol. Cell
A minus-end-directed kinesin with plus-end tracking protein activity is involved in spindle morphogenesis
Mol. Biol. Cell
Cortactin branches out: roles in regulating protrusive actin dynamics
Cell Motil. Cytoskeleton
Toward reconstitution of in vivo microtubule dynamics in vitro
Bioessays
Adenomatous polyposis coli (APC): a multi-functional tumor suppressor gene
J. Cell Sci.
The spectraplakin short stop is an actin-microtubule crosslinker that contributes to organization of the microtubule network
Mol. Biol. Cell
Structural transitions at microtubule ends correlate with their dynamic properties in Xenopus egg extracts
J. Cell Biol.
Regulation and function of the interaction between the APC tumour suppressor protein and EB1
Oncogene
Evidence that an interaction between EB1 and p150(Glued) is required for the formation and maintenance of a radial microtubule array anchored at the centrosome
Mol. Biol. Cell
Suppression of nuclear oscillations in Saccharomyces cerevisiae expressing Glu tubulin
Proc. Natl Acad. Sci. USA
Role of APC and its binding partners in regulating microtubules in mitosis
Adv. Exp. Med. Biol.
MCAK-independent functions of ch-Tog/XMAP215 in microtubule plus-end dynamics
Mol. Cell. Biol.
CDK5RAP2 functions in centrosome to spindle pole attachment and DNA damage response
J. Cell Biol.
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2021, Developmental CellCitation Excerpt :The end-binding (EB) family of proteins are the master regulators at the growing microtubule end where they recruit an entire network of proteins that synergize to regulate microtubule dynamics (reviewed in Akhmanova and Steinmetz [2010a]). Among them, CLIP-170 is expressed in mammals, invertebrates, and yeast (Akhmanova et al., 2005; reviewed in Gouveia and Akhmanova [2010]), and its association with microtubules is enhanced by tubulin tyrosination (Bieling et al., 2008). Biochemical and structural studies showed that this specific recognition is mediated by the N-terminal cytoskeleton-associated protein glycine-rich (CAP-Gly) domains of CLIP-170 that recognize the terminal tyrosine in the -EEY motif present both in the C-terminal tail of α-tubulin and EB1 (Bjelić et al., 2012; Bieling et al., 2008; Mishima et al., 2007; Weisbrich et al., 2007).
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2021, Progress in Molecular Biology and Translational ScienceCitation Excerpt :EBs, referred to as part of the MT plus-end tracking protein (+ TIPs) family, decorate polymerized MT plus-ends54 and can directly affect MT dynamics.55 There are three mammalian end-binding proteins: EB1, EB2, and EB3.56 EB1 and EB3 proteins generate homo- and heterodimers, an essential feature required for the plus-end tracking behavior of the EBs.57
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2016, CellCitation Excerpt :The tyrosine is added back to soluble tubulin as part of the detyrosination/tyrosination cycle (Raybin and Flavin, 1975; Szyk et al., 2011). The C-terminal tyrosine is an ON/OFF signal for the recruitment of microtubule regulators such as plus-end-binding proteins and motors (Peris et al., 2009; reviewed in Garnham and Roll-Mecak, 2012; Gouveia and Akhmanova, 2010). Experiments with recombinant human tubulin with or without the α-tubulin C-terminal tyrosine show that neither microtubule binding nor severing is significantly affected by detyrosination (Figure 3B).
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