Minimal plus-end tracking unit of the cytoplasmic linker protein CLIP-170.
Cytoplasmic linker protein 170 (CLIP-170) is the prototype microtubule (MT) plus-end tracking protein (+TIP) and is involved in regulating MT dynamics. A comprehensive understanding of the process by which CLIP-170 tracks MT plus ends would provide insight into its function. However, the precise molecular mechanism of CLIP-170 +TIP behavior is unknown, and many potential models have been presented. Here, by separating the two CLIP-170 CAP-Gly domains and their adjacent serine-rich regions into fragments of varied size, we have characterized the minimal plus-end tracking unit of CLIP-170 in vivo. Each CLIP-170 fragment was also characterized for its tubulin polymerization activity in vitro. We found that the two CAP-Gly domains have different activities, whereas CAP-Gly-1 appears incompetent to mediate either +TIP behavior or MT nucleation, a CLIP-170 fragment consisting of the second CAP-Gly domain and its adjacent serine-rich region can both track MT plus ends in vivo and induce tubulin polymerization in vitro. These observations complement recent work on CLIP-170 fragments, demonstrate that CAP-Gly motifs do not require dimerization for +TIP and polymerization-promoting activities, and provide insight into CLIP-170 function and mechanism.
Gupta
Kamlesh K
KK
Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA.
Paulson
Benjamin A
BA
Folker
Eric S
ES
Charlebois
Blake
B
Hunt
Alan J
AJ
Goodson
Holly V
HV
D020816:Amino Acid Motifs / Q000502:physiology; D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism*; D008870:Microtubules / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary / Q000502:physiology; D013552:Swine; D014404:Tubulin / Q000235:genetics / Q000378:metabolism*
D008869:Microtubule-Associated Proteins; D009363:Neoplasm Proteins; D014404:Tubulin; C076744:cytoplasmic linker protein 170