Identification of residues which regulate activity of the STE20-related kinase hMINK.
Activity of the STE20-related kinase hMINK was investigated. hMINK was expressed widely, though not ubiquitously, in human tissues; highest levels being found in haematopoietic tissues but also in brain, placenta, and lung. Mutagenesis revealed that T(191) and Y(193) in the substrate recognition loop of the catalytic domain were critical for kinase activity against exogenous substrates and autophosphorylation. A mutation on T(187) showed reduced enzymatic activity against exogenous substrates but retained autophosphorylation activity. Phosphorylation was confirmed by the use of a phospho-specific T(187) antibody. hMINK activated the JNK signal transduction pathway and optimal JNK activation occurred when the C-terminus was deleted. In addition, overexpression of the C-terminal domain devoid of kinase activity also resulted in significant activation of the JNK pathway. These data suggest that hMINK requires an activation step that dissociates the C terminal, thereby freeing the catalytic domain to interact with substrates. Models for receptor-mediated activation of hMINK are discussed.
Lim
Jaeseung
J
Yamanouchi Research Institute, Littlemore Park, Oxford, OX4 4SX, UK.
Lennard
Andrew
A
Sheppard
Paul W
PW
Kellie
Stuart
S
D000595:Amino Acid Sequence; D000918:Antibody Specificity; D002460:Cell Line; D003001:Cloning, Molecular; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D048031:JNK Mitogen-Activated Protein Kinases; D007668:Kidney / Q000166:cytology / Q000378:metabolism; D020930:MAP Kinase Kinase Kinases; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009928:Organ Specificity; D010766:Phosphorylation; D015221:Potassium Channels / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D024642:Potassium Channels, Voltage-Gated; D017346:Protein Serine-Threonine Kinases / Q000235:genetics*; D017434:Protein Structure, Tertiary / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins; D013329:Structure-Activity Relationship
D047908:Intracellular Signaling Peptides and Proteins; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D029701:Saccharomyces cerevisiae Proteins; C059983:potassium channel protein I(sk); D017346:Protein Serine-Threonine Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D020930:MAP Kinase Kinase Kinases; C078754:STE20 protein, S cerevisiae