title: Cloning and Initial Functional Characterization of Mlk4α and Mlk4β.
abstract: We have cloned a novel human mixed-lineage kinase gene, MLK4. Two alternatively spliced forms, MLK4α (580 aa) and MLK4β (1036 aa), have been identified and mapped to chromosomal band 1q42. MLK4 shows high amino acid homology to the kinase catalytic domain of MLK3 (72%), MLK1 (71%) and MLK2 (69%). Strong expression of MLK4 was detected in the human pancreas and kidneys. pCMV-MLK4β c-myc-tagged protein (human) was expressed in the cytoplasm and nucleus of transiently transfected COS-1 cells, while pCMV-MLK4α c-myc-tagged protein (human) was expressed in cytoplasm only. Both MLK4 isoforms reduced the colony formation ability of MCF7 cells by 85%-95% and almost totally suppressed cell proliferation in the CyQUANT cell proliferation assay. Human pCMV-MLK4β transgenic mice expressed the MLK4β in all tissues examined but no phenotypic abnormalities were observed. Thus, in this work, we present the cloning and sequencing of MLK4α and MLK4β for the first time; the data obtained suggest that MLK4 may function as a MAP kinase.
authors.affiliation: Department of Microbiology, Tumor and Cell Biology, Department of Clinical Science and Education, Södersjukhuset, Karolinska Institute, Stockholm, 17177, Sweden. ; Institute of Molecular Biology and Genetics, Ukrainian National Academy of Sciences, Kiev, 03143, Ukraine.
authors.forename: Vladimir I
authors.initials: VI
authors.lastname: Kashuba
authors.affiliation: Department of Microbiology, Tumor and Cell Biology, Department of Clinical Science and Education, Södersjukhuset, Karolinska Institute, Stockholm, 17177, Sweden. ; Institute of Molecular Biology and Biophysics, Siberian Division of Russian Academy of Medical Sciences, Novosibirsk, 630117, Russia.
authors.forename: Elvira V
authors.initials: EV
authors.lastname: Grigorieva
authors.affiliation: Institute of Molecular Biology and Genetics, Ukrainian National Academy of Sciences, Kiev, 03143, Ukraine.
authors.forename: Sergei M
authors.initials: SM
authors.lastname: Kvasha
authors.affiliation: Department of Microbiology, Tumor and Cell Biology, Department of Clinical Science and Education, Södersjukhuset, Karolinska Institute, Stockholm, 17177, Sweden. ; Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, 119991, Russia.
authors.forename: Tatiana V
authors.initials: TV
authors.lastname: Pavlova
authors.affiliation: Institute of Cancer Research, 237 Fulham Road, London SW3 6JB, UK.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Grigoriev
authors.affiliation: Department of Microbiology, Tumor and Cell Biology, Department of Clinical Science and Education, Södersjukhuset, Karolinska Institute, Stockholm, 17177, Sweden.
authors.forename: Alexei
authors.initials: A
authors.lastname: Protopopov
authors.affiliation: Department of Microbiology, Tumor and Cell Biology, Department of Clinical Science and Education, Södersjukhuset, Karolinska Institute, Stockholm, 17177, Sweden. ; Pavlov Institute of Physiology, Russian Academy of Sciences, St. Petersburg, 199034, Russia.
authors.forename: Olga
authors.initials: O
authors.lastname: Kharchenko
authors.affiliation: Department of Microbiology, Tumor and Cell Biology, Department of Clinical Science and Education, Södersjukhuset, Karolinska Institute, Stockholm, 17177, Sweden.
authors.forename: Rinat
authors.initials: R
authors.lastname: Gizatullin
authors.affiliation: Institute of Molecular Biology and Genetics, Ukrainian National Academy of Sciences, Kiev, 03143, Ukraine.
authors.forename: Alla V
authors.initials: AV
authors.lastname: Rynditch
authors.affiliation: Department of Microbiology, Tumor and Cell Biology, Department of Clinical Science and Education, Södersjukhuset, Karolinska Institute, Stockholm, 17177, Sweden. ; Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, 119991, Russia.
authors.forename: Eugene R
authors.initials: ER
authors.lastname: Zabarovsky
keywords: MLK; gene cloning; protein kinase; tumor suppressor gene