These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Cleavage at site A, Glu-642 to Ser-643, of the gizzard myosin heavy chain decreases affinity for actin.
    Author: Ikebe M, Mitra S, Hartshorne DJ.
    Journal: J Biol Chem; 1993 Dec 05; 268(34):25948-51. PubMed ID: 7902357.
    Abstract:
    The actin-activated ATPase activities of subfragment 1 (S1) produced from gizzard myosin by papain or Staphylococcus aureus protease are different. The activity of the latter is lower, in spite of the presence of intact 20,000-dalton light chains. To study this difference, the S. aureus protease S1 was subjected to further proteolysis by papain. This second stage of proteolysis markedly increased actin-activated ATPase, due to a decrease in K(actin) with no change in Vm and increased the affinity of S1 for actin in the presence of ATP. Treatment with papain caused degradation of the 20-kDa light chain, a decrease in the 26-kDa C-terminal domain of S1 and the 68-kDa fragment containing the N-terminal and central domains, and in the appearance and progressive increase of a 94-kDa fragment. The increase in actin-activated ATPase activity was due to the production of the 94-kDa fragment but not due to light chain degradation. Analyses of N-terminal sequences following papain digestion showed that the 94-kDa fragment was formed from a combination of the 68- and 26-kDa fragments. The bond formed probably involved the N-terminal residue of the 26-kDa fragment (Ser-643) and a side chain carboxyl (Glu-642) or amine (Glu-636). From the sequence data site A was identified as Glu-642-Ser-643. These results confirm the importance of site A in actin-binding of gizzard myosin. It is suggested that the sequence Ser-643 and Val-659, as well as the 3 lysine residues, are important for actin binding.
    [Abstract] [Full Text] [Related] [New Search]