Identification and characterization of a lymphocytic Rho-GTPase effector: rhotekin-2.
Rhotekin belongs to the group of proteins containing a Rho-binding domain that are target peptides (effectors) for the Rho-GTPases. We previously identified a novel cDNA with homology to human rhotekin and in this study we cloned and characterized the coding region of this novel 12-exon gene. The ORF encodes a 609 amino-acid protein comprising a Class I Rho-binding domain and pleckstrin homology (PH) domain. Cellular cDNA expression of this new protein, designated Rhotekin-2 (RTKN2), was shown in the cytosol and nucleus of CHO cells. Using bioinformatics and RTPCR we identified three major splice variants, which vary in both the Rho-binding and PH domains. Real-time PCR studies showed exclusive RTKN2 expression in pooled lymphocytes and further purification indicated sole expression in CD4(pos) T-cells and bone marrow-derived B-cells. Gene expression was increased in quiescent T-cells but negligible in activated proliferating cells. In malignant samples expression was absent in myeloid leukaemias, low in most B-cell malignancies and CD8(pos) T-cell malignancies, but very high in CD4(pos)/CD8(pos) T-lymphoblastic lymphoma. As the Rho family is critical in lymphocyte development and function, RTKN2 may play an important role in lymphopoiesis.
Collier
F M
FM
Douglas Hocking Research Institute, Barwon Health, The Geelong Hospital, Geelong, Victoria 3220, Australia. fionac@barwonhealth.org.au
Gregorio-King
C C
CC
Gough
T J
TJ
Talbot
C D
CD
Walder
K
K
Kirkland
M A
MA
D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D020555:GTP-Binding Protein Regulators / Q000032:analysis / Q000235:genetics* / Q000378:metabolism; D015870:Gene Expression; D019337:Hematologic Neoplasms / Q000378:metabolism; D006412:Hematopoietic Stem Cells / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins / Q000032:analysis / Q000235:genetics* / Q000378:metabolism; D008213:Lymphocyte Activation; D016131:Lymphocyte Subsets / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D051381:Rats; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D020741:rho GTP-Binding Proteins / Q000378:metabolism
D020555:GTP-Binding Protein Regulators; D047908:Intracellular Signaling Peptides and Proteins; D020033:Protein Isoforms; C495970:RTKN2 protein, human; D020741:rho GTP-Binding Proteins