HS1 (haematopoietic lineage cell-specific gene protein 1), a prominent substrate of intracellular protein tyrosine kinases in haematopoietic cells, is implicated in the immune response to extracellular stimuli and in cell differentiation induced by cytokines. Although HS1 contains a 37-amino acid tandem repeat motif and a C-terminal Src homology 3 domain and is closely related to the cortical-actin-associated protein cortactin, it lacks the fourth repeat that has been shown to be essential for cortactin binding to filamentous actin (F-actin). In this study, we examined the possible role of HS1 in the regulation of the actin cytoskeleton. Immunofluorescent staining demonstrated that HS1 co-localizes in the cytoplasm of cells with actin-related protein (Arp) 2/3 complex, the primary component of the cellular machinery responsible for de novo actin assembly. Furthermore, recombinant HS1 binds directly to Arp2/3 complex with an equilibrium dissociation constant (Kd) of 880nM. Although HS1 is a modest F-actin-binding protein with a Kd of 400nM, it increases the rate of the actin assembly mediated by Arp2/3 complex, and promotes the formation of branched actin filaments induced by Arp2/3 complex and a constitutively activated peptide of N-WASP (neural Wiskott–Aldrich syndrome protein). Our data suggest that HS1, like cortactin, plays an important role in the modulation of actin assembly.
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April 2003
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Research Article|
April 15 2003
Haematopoietic lineage cell-specific protein 1 (HS1) promotes actin-related protein (Arp) 2/3 complex-mediated actin polymerization
Takehito URUNO;
Takehito URUNO
∗Department of Experimental Pathology, Jerome H. Holland Laboratory for the Biomedical Sciences, American Red Cross, 15601 Crabbs Branch Way, Rockville, MD 20855, U.S.A.
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Peijun ZHANG;
Peijun ZHANG
∗Department of Experimental Pathology, Jerome H. Holland Laboratory for the Biomedical Sciences, American Red Cross, 15601 Crabbs Branch Way, Rockville, MD 20855, U.S.A.
†Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, People's Republic of China
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Jiali LIU;
Jiali LIU
∗Department of Experimental Pathology, Jerome H. Holland Laboratory for the Biomedical Sciences, American Red Cross, 15601 Crabbs Branch Way, Rockville, MD 20855, U.S.A.
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Jian-Jiang HAO;
Jian-Jiang HAO
∗Department of Experimental Pathology, Jerome H. Holland Laboratory for the Biomedical Sciences, American Red Cross, 15601 Crabbs Branch Way, Rockville, MD 20855, U.S.A.
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Xi ZHAN
Xi ZHAN
1
∗Department of Experimental Pathology, Jerome H. Holland Laboratory for the Biomedical Sciences, American Red Cross, 15601 Crabbs Branch Way, Rockville, MD 20855, U.S.A.
‡Department of Cell Biology and Anatomy, The George Washington University, Washington, DC 20001, U.S.A.
1To whom correspondence should be addressed, at the Department of Experimental Pathology, Jerome H. Holland Laboratory for the Biomedical Sciences (e-mail zhanx@usa.redcross.org).
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Publisher: Portland Press Ltd
Received:
November 18 2002
Revision Received:
January 03 2003
Accepted:
January 20 2003
Accepted Manuscript online:
January 20 2003
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London ©2003
2003
Biochem J (2003) 371 (2): 485–493.
Article history
Received:
November 18 2002
Revision Received:
January 03 2003
Accepted:
January 20 2003
Accepted Manuscript online:
January 20 2003
Citation
Takehito URUNO, Peijun ZHANG, Jiali LIU, Jian-Jiang HAO, Xi ZHAN; Haematopoietic lineage cell-specific protein 1 (HS1) promotes actin-related protein (Arp) 2/3 complex-mediated actin polymerization. Biochem J 15 April 2003; 371 (2): 485–493. doi: https://doi.org/10.1042/bj20021791
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