title: TCL/RhoJ Plasma Membrane Localization and Nucleotide Exchange Is Coordinately Regulated by Amino Acids within the N Terminus and a Distal Loop Region.
abstract: TCL/RhoJ is a Cdc42-related Rho GTPase with reported activities in endothelial cell biology and angiogenesis, metastatic melanoma, and corneal epithelial cells; however, less is known about how it is inherently regulated in comparison to its closest homologues TC10 and Cdc42. TCL has an N-terminal extension of 18 amino acids in comparison to Cdc42, but the function of this amino acid sequence has not been elucidated. A truncation mutant lacking the N terminus (ΔN) was found to alter TCL plasma membrane localization and nucleotide binding, and additional truncation and point mutants mapped the alterations of TCL biochemistry to amino acids 17-20. Interestingly, whereas the TCL ΔN mutant clearly influenced nucleotide exchange, deletion of the N terminus from its closest homologue, TC10, did not have a similar effect. Chimeras of TCL and TC10 revealed amino acids 121-129 of TCL contributed to the differences in nucleotide loading. Together, these results identify amino acids within the N terminus and a loop region distal to the nucleotide binding pocket of TCL capable of allosterically regulating nucleotide exchange and thus influence membrane association of the protein.
authors.affiliation: From the Biology Department, Bemidji State University, Bemidji, Minnesota 56601.
authors.forename: Karly L
authors.initials: KL
authors.lastname: Ackermann
authors.affiliation: From the Biology Department, Bemidji State University, Bemidji, Minnesota 56601.
authors.forename: Rebecca R
authors.initials: RR
authors.lastname: Florke
authors.affiliation: From the Biology Department, Bemidji State University, Bemidji, Minnesota 56601.
authors.forename: Shannon S
authors.initials: SS
authors.lastname: Reyes
authors.affiliation: From the Biology Department, Bemidji State University, Bemidji, Minnesota 56601.
authors.forename: Brooke R
authors.initials: BR
authors.lastname: Tader
authors.affiliation: From the Biology Department, Bemidji State University, Bemidji, Minnesota 56601 mhamann@bemidjistate.edu.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Hamann
mesh_terms: D000494:Allosteric Regulation; D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D002462:Cell Membrane / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D008958:Models, Molecular; D009711:Nucleotides / Q000378:metabolism*; D011487:Protein Conformation; D017384:Sequence Deletion; D020741:rho GTP-Binding Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D009711:Nucleotides; C417188:RHOJ protein, human; D020741:rho GTP-Binding Proteins
keywords: CDC42; GTPase; Rho (Rho GTPase); RhoJ; TCL; allosteric regulation; cell biology; membrane trafficking; small GTPase; vesicles