The MAP kinase kinase kinase MLK2 co-localizes with activated JNK along microtubules and associates with kinesin superfamily motor KIF3.
The MLK (mixed lineage) ser/thr kinases are most closely related to the MAP kinase kinase kinase family. In addition to a kinase domain, MLK1, MLK2 and MLK3 each contain an SH3 domain, a leucine zipper domain and a potential Rac/Cdc42 GTPase-binding (CRIB) motif. The C-terminal regions of the proteins are essentially unrelated. Using yeast two-hybrid analysis and in vitro dot-blots, we show that MLK2 and MLK3 interact with the activated (GTP-bound) forms of Rac and Cdc42, with a slight preference for Rac. Transfection of MLK2 into COS cells leads to strong and constitutive activation of the JNK (c-Jun N-terminal kinase) MAP kinase cascade, but also to activation of ERK (extracellular signal-regulated kinase) and p38. When expressed in fibroblasts, MLK2 co-localizes with active, dually phosphorylated JNK1/2 to punctate structures along microtubules. In an attempt to identify proteins that affect the activity and localization of MLK2, we have screened a yeast two-hybrid cDNA library. MLK2 and MLK3 interact with members of the KIF3 family of kinesin superfamily motor proteins and with KAP3A, the putative targeting component of KIF3 motor complexes, suggesting a potential link between stress activation and motor protein function.
Nagata
K i
Ki
MRC Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT, UK.
Puls
A
A
Futter
C
C
Aspenstrom
P
P
Schaefer
E
E
Nakata
T
T
Hirokawa
N
N
Hall
A
A
D048948:14-3-3 Proteins; D016475:3T3 Cells; D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D002135:Calcium-Binding Proteins / Q000378:metabolism; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000378:metabolism; D002465:Cell Movement; D003598:Cytoskeletal Proteins; D004789:Enzyme Activation; D019204:GTP-Binding Proteins / Q000378:metabolism; D051597:Hippocalcin; D048031:JNK Mitogen-Activated Protein Kinases; D016547:Kinesins / Q000378:metabolism*; D020930:MAP Kinase Kinase Kinases; D051379:Mice; D008845:Microinjections; D008870:Microtubules / Q000201:enzymology*; D020928:Mitogen-Activated Protein Kinases; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D014446:Tyrosine 3-Monooxygenase; D020846:cdc42 GTP-Binding Protein, Saccharomyces cerevisiae; D020744:rac GTP-Binding Proteins
D048948:14-3-3 Proteins; D048868:Adaptor Proteins, Signal Transducing; D002135:Calcium-Binding Proteins; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D003598:Cytoskeletal Proteins; C484407:KIFAP3 protein, human; C490202:Kif3a protein, mouse; D009419:Nerve Tissue Proteins; D011506:Proteins; D011994:Recombinant Proteins; D051597:Hippocalcin; C100815:Kifap3 protein, mouse; D014446:Tyrosine 3-Monooxygenase; D017346:Protein Serine-Threonine Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D020930:MAP Kinase Kinase Kinases; C490541:Map3k10 protein, mouse; D019204:GTP-Binding Proteins; D016547:Kinesins; D020846:cdc42 GTP-Binding Protein, Saccharomyces cerevisiae; D020744:rac GTP-Binding Proteins