Ca2+-calmodulin binds to the carboxyl-terminal domain of dystrophin.
The unique COOH-terminal domain of dystrophin (mouse dystrophin protein sequences 3266-3678) was expressed as a chimeric fusion protein (with the maltose-binding protein), and its binding to calmodulin was assessed. This fusion protein, called DysS9, bound to calmodulin-Sepharose, bound biotinylated calmodulin, caused characteristic changes in the fluorescence emission spectrum of dansyl-calmodulin, and had an apparent affinity for dansyl-calmodulin of 54 nM. Binding in each case was Ca2+-dependent. The maltose-binding protein does not bind calmodulin, and thus binding resides in the dystrophin-derived sequences. Deletion mutation experiments further localize the high affinity calmodulin binding to mouse dystrophin protein sequences 3293-3349, and this domain contains regions with chemical characteristics found in the calmodulin-binding sequences in other proteins. The COOH-terminal domain provides sites of attachment of dystrophin to membrane proteins, and calmodulin binding may modulate these interactions.
Anderson
J T
JT
Department of Biochemistry, University of Tennessee, Memphis, Tennessee 38163, USA.
Rogers
R P
RP
Jarrett
H W
HW
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism*; D002147:Calmodulin / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics; D002417:Cattle; D016189:Dystrophin / Q000235:genetics / Q000378:metabolism*; D058619:Maltose-Binding Proteins; D051379:Mice; D008969:Molecular Sequence Data; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D017384:Sequence Deletion
D002147:Calmodulin; D002352:Carrier Proteins; D016189:Dystrophin; D058619:Maltose-Binding Proteins; D011993:Recombinant Fusion Proteins; D002118:Calcium