RESUMO
Ste20p (sterile 20 protein) is a putative yeast mitogen-activated protein kinase kinase kinase kinase (MAP4K) involved in the mating pathway. Its homologs in mammals, Drosophila, Caenorhabditis elegans and other organisms make up a large emerging group of protein kinases including 28 members in human. The Ste20 group kinases are further divided into the p21-activated kinase (PAK) and germinal center kinase (GCK) families. They are characterized by the presence of a conserved kinase domain and a noncatalytic region of great structural diversity that enables the kinases to interact with various signaling molecules and regulatory proteins of the cytoskeleton. This review describes the phylogenetic relationships of the Ste20 group kinases based on discussions with many researchers in this field. With the newly established phylogenetic relationships, crucial arguments can be advanced regarding the functions of these kinases as upstream activators of the MAPK pathways and possible activity as MAP4Ks. Their involvement in apoptosis, morphogenesis and cytoskeletal rearrangements is also discussed.
Assuntos
Apoptose/fisiologia , Proteínas de Drosophila , Sistema de Sinalização das MAP Quinases/fisiologia , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas de Saccharomyces cerevisiae , Animais , Quinases do Centro Germinativo , Humanos , Peptídeos e Proteínas de Sinalização Intracelular , MAP Quinase Quinase Quinases , Modelos Biológicos , Filogenia , Proteínas Serina-Treonina Quinases/genética , Quinases Ativadas por p21RESUMO
A new germinal center kinase (GCK) family kinase, Misshapen/NIKs-related kinase (MINK), has been cloned and its expression has been characterized in several tissues and various developmental stages of the mouse brain. MINK encodes a 1300 amino acid polypeptide, consisting of an N-terminal kinase domain, a proline-rich intermediate region, and a C-terminal GCK homology region. The expression of MINK is up-regulated during the postnatal development of the mouse brain. MINK activates the cJun N-terminal kinase and the p38 pathways.
Assuntos
Encéfalo/enzimologia , Proteínas do Tecido Nervoso/genética , Proteínas Serina-Treonina Quinases/genética , Sequência de Aminoácidos , Animais , Encéfalo/crescimento & desenvolvimento , Linhagem Celular , Clonagem Molecular , Ativação Enzimática , Regulação da Expressão Gênica no Desenvolvimento , Quinases do Centro Germinativo , Camundongos , Proteínas Quinases Ativadas por Mitógeno/genética , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Dados de Sequência Molecular , Proteínas do Tecido Nervoso/química , Filogenia , Proteínas Serina-Treonina Quinases/química , RNA Mensageiro/metabolismo , Transdução de Sinais , Transfecção , Regulação para CimaRESUMO
The kinetics of ice-nucleus assembly from newly synthesized nucleation protein were observed following induction of nucleation gene expression in the heterologous host Escherichia coli. Assembly was significantly slower for the small proportion of ice nuclei active above -4.4 degrees C; this was consistent with the belief that these nuclei comprise the largest aggregates of nucleation protein. The kinetics of nucleus degradation were followed after inhibiting protein synthesis. Nucleation activity and protein showed a concerted decay, indicating that most of the functional ice nuclei are in equilibrium with a single cellular pool of nucleation protein. A minority of the ice nuclei decayed much more slowly than the majority; presumably their nucleation protein was distinct either by virtue of different structure or different subcellular compartmentalization, or because of its presence in a metabolically distinct subpopulation of cells.
