XPLN, a guanine nucleotide exchange factor for RhoA and RhoB, but not RhoC

William T Arthur; Shawn M Ellerbroek; Channing J Der; Keith Burridge; Krister Wennerberg

doi:10.1074/jbc.M207401200

XPLN, a guanine nucleotide exchange factor for RhoA and RhoB, but not RhoC

William T Arthur, Shawn M Ellerbroek, Channing J Der, Keith Burridge, Krister Wennerberg

85 Citations (Scopus)

Abstract

Rho proteins cycle between an inactive, GDP-bound state and an active, GTP-bound state. Activation of these GTPases is mediated by guanine nucleotide exchange factors (GEFs), which promote GDP to GTP exchange. In this study we have characterized XPLN, a Rho family GEF. Like other Rho GEFs, XPLN contains a tandem Dbl homology and pleckstrin homology domain topography, but lacks homology with other known functional domains or motifs. XPLN protein is expressed in the brain, skeletal muscle, heart, kidney, platelets, and macrophage and neuronal cell lines. In vitro, XPLN stimulates guanine nucleotide exchange on RhoA and RhoB, but not RhoC, RhoG, Rac1, or Cdc42. Consistent with these data, XPLN preferentially associates with RhoA and RhoB. The specificity of XPLN for RhoA and RhoB, but not RhoC, is surprising given that they share over 85% sequence identity. We determined that the inability of XPLN to exchange RhoC is mediated by isoleucine 43 in RhoC, a position occupied by valine in RhoA and RhoB. When expressed in cells, XPLN activates RhoA and RhoB, but not RhoC, and stimulates the assembly of stress fibers and focal adhesions in a Rho kinase-dependent manner. We also found that XPLN possesses transforming activity, as determined by focus formation assays. In conclusion, here we describe a Rho family GEF that can discriminate between the closely related RhoA, RhoB, and RhoC, possibly giving insight to the divergent functions of these three proteins.

Original language	English
Journal	The Journal of Biological Chemistry
Volume	277
Issue number	45
Pages (from-to)	42964-72
Number of pages	9
ISSN	0021-9258
DOIs	https://doi.org/10.1074/jbc.M207401200
Publication status	Published - 8 Nov 2002
Externally published	Yes

Keywords

3T3 Cells
Amino Acid Sequence
Animals
Brain/metabolism
Cloning, Molecular
Focal Adhesions/physiology
Gene Library
Guanine Nucleotide Exchange Factors/chemistry
HeLa Cells
Humans
Kinetics
Leukemia, Myeloid
Mice
Molecular Sequence Data
Organ Specificity
Rabbits
Recombinant Proteins/chemistry
Rho Guanine Nucleotide Exchange Factors
Sequence Alignment
Sequence Homology, Amino Acid
Substrate Specificity
Transfection
ras Proteins
rho GTP-Binding Proteins/metabolism
rhoA GTP-Binding Protein/metabolism
rhoB GTP-Binding Protein/metabolism
rhoC GTP-Binding Protein

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10.1074/jbc.M207401200

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title = "XPLN, a guanine nucleotide exchange factor for RhoA and RhoB, but not RhoC",

abstract = "Rho proteins cycle between an inactive, GDP-bound state and an active, GTP-bound state. Activation of these GTPases is mediated by guanine nucleotide exchange factors (GEFs), which promote GDP to GTP exchange. In this study we have characterized XPLN, a Rho family GEF. Like other Rho GEFs, XPLN contains a tandem Dbl homology and pleckstrin homology domain topography, but lacks homology with other known functional domains or motifs. XPLN protein is expressed in the brain, skeletal muscle, heart, kidney, platelets, and macrophage and neuronal cell lines. In vitro, XPLN stimulates guanine nucleotide exchange on RhoA and RhoB, but not RhoC, RhoG, Rac1, or Cdc42. Consistent with these data, XPLN preferentially associates with RhoA and RhoB. The specificity of XPLN for RhoA and RhoB, but not RhoC, is surprising given that they share over 85% sequence identity. We determined that the inability of XPLN to exchange RhoC is mediated by isoleucine 43 in RhoC, a position occupied by valine in RhoA and RhoB. When expressed in cells, XPLN activates RhoA and RhoB, but not RhoC, and stimulates the assembly of stress fibers and focal adhesions in a Rho kinase-dependent manner. We also found that XPLN possesses transforming activity, as determined by focus formation assays. In conclusion, here we describe a Rho family GEF that can discriminate between the closely related RhoA, RhoB, and RhoC, possibly giving insight to the divergent functions of these three proteins.",

keywords = "3T3 Cells, Amino Acid Sequence, Animals, Brain/metabolism, Cloning, Molecular, Focal Adhesions/physiology, Gene Library, Guanine Nucleotide Exchange Factors/chemistry, HeLa Cells, Humans, Kinetics, Leukemia, Myeloid, Mice, Molecular Sequence Data, Organ Specificity, Rabbits, Recombinant Proteins/chemistry, Rho Guanine Nucleotide Exchange Factors, Sequence Alignment, Sequence Homology, Amino Acid, Substrate Specificity, Transfection, ras Proteins, rho GTP-Binding Proteins/metabolism, rhoA GTP-Binding Protein/metabolism, rhoB GTP-Binding Protein/metabolism, rhoC GTP-Binding Protein",

author = "Arthur, {William T} and Ellerbroek, {Shawn M} and Der, {Channing J} and Keith Burridge and Krister Wennerberg",

year = "2002",

month = nov,

day = "8",

doi = "10.1074/jbc.M207401200",

language = "English",

volume = "277",

pages = "42964--72",

journal = "Journal of Biological Chemistry",

issn = "0021-9258",

publisher = "American Society for Biochemistry and Molecular Biology, Inc.",

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TY - JOUR

T1 - XPLN, a guanine nucleotide exchange factor for RhoA and RhoB, but not RhoC

AU - Arthur, William T

AU - Ellerbroek, Shawn M

AU - Der, Channing J

AU - Burridge, Keith

AU - Wennerberg, Krister

PY - 2002/11/8

Y1 - 2002/11/8

N2 - Rho proteins cycle between an inactive, GDP-bound state and an active, GTP-bound state. Activation of these GTPases is mediated by guanine nucleotide exchange factors (GEFs), which promote GDP to GTP exchange. In this study we have characterized XPLN, a Rho family GEF. Like other Rho GEFs, XPLN contains a tandem Dbl homology and pleckstrin homology domain topography, but lacks homology with other known functional domains or motifs. XPLN protein is expressed in the brain, skeletal muscle, heart, kidney, platelets, and macrophage and neuronal cell lines. In vitro, XPLN stimulates guanine nucleotide exchange on RhoA and RhoB, but not RhoC, RhoG, Rac1, or Cdc42. Consistent with these data, XPLN preferentially associates with RhoA and RhoB. The specificity of XPLN for RhoA and RhoB, but not RhoC, is surprising given that they share over 85% sequence identity. We determined that the inability of XPLN to exchange RhoC is mediated by isoleucine 43 in RhoC, a position occupied by valine in RhoA and RhoB. When expressed in cells, XPLN activates RhoA and RhoB, but not RhoC, and stimulates the assembly of stress fibers and focal adhesions in a Rho kinase-dependent manner. We also found that XPLN possesses transforming activity, as determined by focus formation assays. In conclusion, here we describe a Rho family GEF that can discriminate between the closely related RhoA, RhoB, and RhoC, possibly giving insight to the divergent functions of these three proteins.

AB - Rho proteins cycle between an inactive, GDP-bound state and an active, GTP-bound state. Activation of these GTPases is mediated by guanine nucleotide exchange factors (GEFs), which promote GDP to GTP exchange. In this study we have characterized XPLN, a Rho family GEF. Like other Rho GEFs, XPLN contains a tandem Dbl homology and pleckstrin homology domain topography, but lacks homology with other known functional domains or motifs. XPLN protein is expressed in the brain, skeletal muscle, heart, kidney, platelets, and macrophage and neuronal cell lines. In vitro, XPLN stimulates guanine nucleotide exchange on RhoA and RhoB, but not RhoC, RhoG, Rac1, or Cdc42. Consistent with these data, XPLN preferentially associates with RhoA and RhoB. The specificity of XPLN for RhoA and RhoB, but not RhoC, is surprising given that they share over 85% sequence identity. We determined that the inability of XPLN to exchange RhoC is mediated by isoleucine 43 in RhoC, a position occupied by valine in RhoA and RhoB. When expressed in cells, XPLN activates RhoA and RhoB, but not RhoC, and stimulates the assembly of stress fibers and focal adhesions in a Rho kinase-dependent manner. We also found that XPLN possesses transforming activity, as determined by focus formation assays. In conclusion, here we describe a Rho family GEF that can discriminate between the closely related RhoA, RhoB, and RhoC, possibly giving insight to the divergent functions of these three proteins.

KW - 3T3 Cells

KW - Amino Acid Sequence

KW - Animals

KW - Brain/metabolism

KW - Cloning, Molecular

KW - Focal Adhesions/physiology

KW - Gene Library

KW - Guanine Nucleotide Exchange Factors/chemistry

KW - HeLa Cells

KW - Humans

KW - Kinetics

KW - Leukemia, Myeloid

KW - Mice

KW - Molecular Sequence Data

KW - Organ Specificity

KW - Rabbits

KW - Recombinant Proteins/chemistry

KW - Rho Guanine Nucleotide Exchange Factors

KW - Sequence Alignment

KW - Sequence Homology, Amino Acid

KW - Substrate Specificity

KW - Transfection

KW - ras Proteins

KW - rho GTP-Binding Proteins/metabolism

KW - rhoA GTP-Binding Protein/metabolism

KW - rhoB GTP-Binding Protein/metabolism

KW - rhoC GTP-Binding Protein

U2 - 10.1074/jbc.M207401200

DO - 10.1074/jbc.M207401200

M3 - Journal article

C2 - 12221096

SN - 0021-9258

VL - 277

SP - 42964

EP - 42972

JO - Journal of Biological Chemistry

JF - Journal of Biological Chemistry

IS - 45

ER -

XPLN, a guanine nucleotide exchange factor for RhoA and RhoB, but not RhoC

Abstract

Keywords

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