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J. Biol. Chem., Vol. 282, Issue 41, 29874-29881, October 12, 2007

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Identification of a Redox-sensitive Cysteine in GCP60 That Regulates Its Interaction with Golgin-160^*

From the Department of Cell Biology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205

Golgin-160 is ubiquitously expressed in vertebrates. It localizes to the cytoplasmic side of the Golgi and has a large C-terminal coiled-coil domain. The noncoiled-coil N-terminal head domain contains Golgi targeting information, a cryptic nuclear localization signal, and three caspase cleavage sites. Caspase cleavage of the golgin-160 head domain generates different fragments that can translocate to the nucleus by exposing the nuclear localization signal. We have previously shown that GCP60, a Golgi resident protein, interacts weakly with the golgin-160 head domain but has a strong interaction with one of the caspase-generated golgin-160 fragments (residues 140–311). This preferential interaction increases the Golgi retention of the golgin-160 fragment in cells overexpressing GCP60. Here we studied the interaction of golgin-160-(140–311) with GCP60 and identified a single cysteine residue in GCP60 (Cys-463) that is critical for the interaction of the two proteins. Mutation of the cysteine blocked the interaction in vitro and disrupted the ability to retain the golgin-160 fragment at the Golgi in cells. We also found that Cys-463 is redox-sensitive; in its reduced form, interaction with golgin-160 was diminished or abolished, whereas oxidation of the Cys-463 by hydrogen peroxide restored the interaction. In addition, incubation with a nitric oxide donor promoted this interaction in vitro. These findings suggest that nuclear translocation of golgin-160-(140–311) is a highly coordinated event regulated not only by cleavage of the golgin-160 head but also by the oxidation state of GCP60.

Received for publication, July 16, 2007 , and in revised form, August 15, 2007.

^* This work was supported by National Institutes of Health Grant GM42522 (to C. E. M.). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

¹ To whom correspondence should be addressed: Dept. of Cell Biology, The Johns Hopkins University School of Medicine, 725 Wolfe St., Baltimore, MD 21205. Tel.: 410-955-1809; Fax: 410-955-4129; E-mail: machamer{at}jhmi.edu.

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