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Krit 1 interactions with microtubules and membranes are regulated by Rap1 and integrin cytoplasmic domain associated protein-1
- Source :
- FEBS Journal, FEBS Journal, Wiley, 2007, 274 (21), pp.5518-32. ⟨10.1111/j.1742-4658.2007.06068.x⟩
- Publication Year :
- 2007
- Publisher :
- HAL CCSD, 2007.
-
Abstract
- International audience; The small G protein Rap1 regulates diverse cellular processes such as integrin activation, cell adhesion, cell-cell junction formation and cell polarity. It is crucial to identify Rap1 effectors to better understand the signalling pathways controlling these processes. Krev interaction trapped 1 (Krit1), a protein with FERM (band four-point-one/ezrin/radixin/moesin) domain, was identified as a Rap1 partner in a yeast two-hybrid screen, but this interaction was not confirmed in subsequent studies. As the evidence suggests a role for Krit1 in Rap1-dependent pathways, we readdressed this question. In the present study, we demonstrate by biochemical assays that Krit1 interacts with Rap1A, preferentially its GTP-bound form. We show that, like other FERM proteins, Krit1 adopts two conformations: a closed conformation in which its N-terminal NPAY motif interacts with its C-terminus and an opened conformation bound to integrin cytoplasmic domain associated protein (ICAP)-1, a negative regulator of focal adhesion assembly. We show that a ternary complex can form in vitro between Krit1, Rap1 and ICAP-1 and that Rap1 binds the Krit1 FERM domain in both closed and opened conformations. Unlike ICAP-1, Rap1 does not open Krit1. Using sedimentation assays, we show that Krit1 binds in vitro to microtubules through its N- and C-termini and that Rap1 and ICAP-1 inhibit Krit1 binding to microtubules. Consistently, YFP-Krit1 localizes on cyan fluorescent protein-labelled microtubules in baby hamster kidney cells and is delocalized from microtubules upon coexpression with activated Rap1V12. Finally, we show that Krit1 binds to phosphatidylinositol 4,5-P(2)-containing liposomes and that Rap1 enhances this binding. Based on these results, we propose a model in which Krit1 would be delivered by microtubules to the plasma membrane where it would be captured by Rap1 and ICAP-1.
- Subjects :
- endocrine system
Rap1
MESH: rap1 GTP-Binding Proteins
MESH: Microtubules
MESH: Transfection
MESH: Models, Biological
MESH: Cricetinae
FERM domain
[SDV.BC]Life Sciences [q-bio]/Cellular Biology
MESH: Two-Hybrid System Techniques
MESH: Membranes
microtubules
enzymes and coenzymes (carbohydrates)
PTB
MESH: Amino Acid Motifs
MESH: Microtubule-Associated Proteins
Krit1
MESH: Protein Conformation
PIP2
MESH: Binding Sites
MESH: Intracellular Signaling Peptides and Proteins
MESH: Animals
MESH: Membrane Proteins
CCM1
MESH: Models, Molecular
Subjects
Details
- Language :
- English
- ISSN :
- 1742464X and 17424658
- Database :
- OpenAIRE
- Journal :
- FEBS Journal, FEBS Journal, Wiley, 2007, 274 (21), pp.5518-32. ⟨10.1111/j.1742-4658.2007.06068.x⟩
- Accession number :
- edsair.dedup.wf.001..dcdcbcf6b8b78c5db8fec06dd92546fc