Twitchin kinase interacts with MAPKAP kinase 2 in Caenorhabditis elegans striated muscle

Mol Biol Cell. 2015 Jun 1;26(11):2096-111. doi: 10.1091/mbc.E14-05-1009. Epub 2015 Apr 7.


In Caenorhabditis elegans, twitchin is a giant polypeptide located in muscle A-bands. The protein kinase of twitchin is autoinhibited by 45 residues upstream (NL) and 60 residues downstream (CRD) of the kinase catalytic core. Molecular dynamics simulation on a twitchin fragment revealed that the NL is released by pulling force. However, it is unclear how the CRD is removed. To identify proteins that may remove the CRD, we performed a yeast two-hybrid screen using twitchin kinase as bait. One interactor is MAK-1, C. elegans orthologue of MAPKAP kinase 2. MAPKAP kinase 2 is phosphorylated and activated by p38 MAP kinase. We demonstrate that the CRD of twitchin is important for binding to MAK-1. mak-1 is expressed in nematode body wall muscle, and antibodies to MAK-1 localize between and around Z-disk analogues and to the edge of A-bands. Whereas unc-22 mutants are completely resistant, mak-1 mutants are partially resistant to nicotine. MAK-1 can phosphorylate twitchin NL-Kin-CRD in vitro. Genetic data suggest the involvement of two other mak-1 paralogues and two orthologues of p38 MAP kinase. These results suggest that MAK-1 is an activator of twitchin kinase and that the p38 MAP kinase pathway may be involved in the regulation of twitchin.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Motifs
  • Animals
  • Caenorhabditis elegans / metabolism*
  • Caenorhabditis elegans Proteins / metabolism*
  • Calmodulin-Binding Proteins / metabolism*
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • Muscle Proteins / metabolism*
  • Muscle, Striated / enzymology*
  • Phosphorylation
  • Protein Binding
  • Protein Serine-Threonine Kinases / metabolism*
  • Sequence Homology, Amino Acid
  • p38 Mitogen-Activated Protein Kinases / metabolism


  • Caenorhabditis elegans Proteins
  • Calmodulin-Binding Proteins
  • Intracellular Signaling Peptides and Proteins
  • Muscle Proteins
  • unc-22 protein, C elegans
  • MAP-kinase-activated kinase 2
  • MAK-1 protein, C elegans
  • Protein Serine-Threonine Kinases
  • p38 Mitogen-Activated Protein Kinases