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J Biol Chem. 2017 Feb 3;292(5):1884-1898. doi: 10.1074/jbc.M116.762393. Epub 2016 Dec 21.

Nuclear Localization of Integrin Cytoplasmic Domain-associated Protein-1 (ICAP1) Influences β1 Integrin Activation and Recruits Krev/Interaction Trapped-1 (KRIT1) to the Nucleus.

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From the Department of Pharmacology and.
From the Department of Pharmacology and
the Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut 06520.


Binding of ICAP1 (integrin cytoplasmic domain-associated protein-1) to the cytoplasmic tails of β1 integrins inhibits integrin activation. ICAP1 also binds to KRIT1 (Krev interaction trapped-1), a protein whose loss of function leads to cerebral cavernous malformation, a cerebrovascular dysplasia occurring in up to 0.5% of the population. We previously showed that KRIT1 functions as a switch for β1 integrin activation by antagonizing ICAP1-mediated inhibition of integrin activation. Here we use overexpression studies, mutagenesis, and flow cytometry to show that ICAP1 contains a functional nuclear localization signal and that nuclear localization impairs the ability of ICAP1 to suppress integrin activation. Moreover, we find that ICAP1 drives the nuclear localization of KRIT1 in a manner dependent upon a direct ICAP1/KRIT1 interaction. Thus, nuclear-cytoplasmic shuttling of ICAP1 influences both integrin activation and KRIT1 localization, presumably impacting nuclear functions of KRIT1.


ICAP1 (integrin cytoplasmic domain-associated protein); KRIT1 (Krev interaction trapped); cell compartmentalization; cerebral cavernous malformation; integrin; protein targeting

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