title: Cloning and expression of a novel MAPKK-like protein kinase, lymphokine-activated killer T-cell-originated protein kinase, specifically expressed in the testis and activated lymphoid cells.
abstract: A novel protein kinase, TOPK (T-LAK cell-originated protein kinase), was isolated from a lymphokine-activated killer T (T-LAK) cell subtraction cDNA fragment library. The open reading frame of the TOPK gene encodes a protein of 322 amino acids, possessing a protein kinase domain profile. The cap site analysis of the 5'-end of TOPK mRNA revealed two forms, a major full-length form and a minor spliced form at the 5'-site, both encoding the same protein. A BLAST homology search and phylogenetic analysis indicated that TOPK is related to dual specific mitogen-activated protein kinase kinase (MAPKK). The transfection of the TOPK gene to COS-7 cells up-regulated a phosphorylation of p38 MAPK but not ERK1/2 or SAPK/JNK. Gel precipitation study indicated that TOPK protein can be associated with p38 in vitro. Tissue distribution of TOPK mRNA expression was specific for the testis, T-LAK cells, activated lymphoid cells, and lymphoid tumors. On the other hand, deactivated T-LAK cells did not show TOPK mRNA expression. These data suggest that TOPK is a newly identified member of a novel MEK3/6-related MAPKK that may be enrolled in the activation of lymphoid cells and support testicular functions.
authors.affiliation: First Department of Pathology, Ehime University School of Medicine, Shigenobu, Ehime 791-0295, Japan. yasuhito@m.ehime-u.ac.jp
authors.forename: Y
authors.initials: Y
authors.lastname: Abe
authors.forename: S
authors.initials: S
authors.lastname: Matsumoto
authors.forename: K
authors.initials: K
authors.lastname: Kito
authors.forename: N
authors.initials: N
authors.lastname: Ueda
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D019556:COS Cells; D002478:Cells, Cultured; D003001:Cloning, Molecular; D006801:Humans; D015979:Killer Cells, Lymphokine-Activated / Q000201:enzymology*; D008213:Lymphocyte Activation; D008214:Lymphocytes / Q000201:enzymology*; D048371:MAP Kinase Kinase 3; D008297:Male; D020929:Mitogen-Activated Protein Kinase Kinases / Q000737:chemistry* / Q000378:metabolism; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D010802:Phylogeny; D011494:Protein Kinases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000737:chemistry* / Q000378:metabolism; D012315:RNA Caps / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid; D013154:Spleen / Q000201:enzymology; D013737:Testis / Q000201:enzymology*; D014158:Transcription, Genetic; D014162:Transfection
chemical_list: D012315:RNA Caps; D012333:RNA, Messenger; D011994:Recombinant Proteins; D011494:Protein Kinases; D011505:Protein-Tyrosine Kinases; D048371:MAP Kinase Kinase 3; C482530:MAP2K3 protein, human; D020929:Mitogen-Activated Protein Kinase Kinases