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The C‐terminal helix in subdomain 4 of the regulatory light chain is essential for myosin regulation.
Author(s) -
Rowe T.,
KendrickJones J.
Publication year - 1993
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1993.tb06177.x
Subject(s) - myosin , myosin light chain kinase , biology , rowe , immunoglobulin light chain , mutant , microbiology and biotechnology , gene , biochemistry , genetics , marketing , antibody , business
In vertebrate smooth/non‐muscle myosins, phosphorylation of the regulatory light chains by a specific calmodulin‐activated kinase controls both myosin head interaction with actin and assembly of the myosin into filaments. Previous studies have shown that the C‐terminal domain of the regulatory light chain is crucial for the regulation of these myosin functions. To further dissect the role of this region of the light chain in myosin regulation, a series of chicken smooth muscle myosin regulatory light chain mutants has been constructed with successive C‐terminal deletions. These mutants were synthesized in Escherichia coli and analysed by their ability to restore Ca2+ regulation to scallop myosin that had been stripped of its native regulatory light chains (‘desensitized’). The results show that regulatory light chain mutants with deletions in the C‐terminal helix in subdomain 4 were able to reform the regulatory Ca2+ binding site on the scallop myosin head, but had lost the ability to suppress scallop myosin filament assembly and interaction with actin in the absence of Ca2+. Further deletions in the C‐terminal domain led to a gradual loss of ability to restore the regulatory Ca2+ binding site. Thus, the regions in the C‐terminal half of the regulatory light chain responsible for myosin regulation can be identified.