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CLASPs attach microtubule plus ends to the cell cortex through a complex with LL5beta.
Gideon Lansbergen1, Ilya Grigoriev, Yuko Mimori-Kiyosue
1MGC Department of Cell Biology and Genetics, Erasmus Medical Center, 3000 DR Rotterdam, The Netherlands.
Developmental Cell
|July 11, 2006
Summary
Researchers identified LL5beta and ELKS as partners of microtubule-stabilizing CLASPs. This complex forms a PIP3-regulated platform at the cell cortex, influencing microtubule stability and cell motility.
Area of Science:
- Cell Biology
- Molecular Biology
- Cytoskeleton Dynamics
Background:
- Cytoskeleton organization is crucial for cell function.
- Microtubule dynamics are regulated by microtubule-associated proteins.
- CLASPs (Cytoplasmic Linker Associated Proteins) stabilize microtubules at the cell cortex.
Purpose of the Study:
- To identify novel CLASP-interacting proteins.
- To elucidate the function of CLASP partners in microtubule regulation.
- To understand the mechanism of CLASP-mediated microtubule stabilization at the cell cortex.
Main Methods:
- Mass spectrometry-based protein interaction assays.
- Immunofluorescence microscopy in HeLa cells and motile fibroblasts.
- Analysis of protein localization and complex formation.
- Investigation of phosphatidylinositol-3,4,5-triphosphate (PIP3) binding and PI3 kinase activity.
Main Results:
- LL5beta and ELKS were identified as CLASP partners.
- The LL5beta-ELKS complex colocalizes with CLASPs at the cell cortex and leading edge.
- LL5beta is essential for CLASP accumulation and microtubule stabilization; ELKS plays an accessory role.
- LL5beta binds PIP3 and is recruited to the cortex independently of microtubules.
- LL5beta-ELKS clusters form near, but do not overlap with, focal adhesions.
Conclusions:
- LL5beta and ELKS form a PIP3-regulated cortical platform.
- This platform recruits CLASPs to stabilize distal microtubule ends.
- The LL5beta-ELKS-CLASP complex contributes to cell motility and cortical organization.