Predicted calmodulin-binding sequence in the gamma subunit of phosphorylase b kinase.
A basic, amphiphilic alpha helix is a structural feature common to a variety of inhibitors of calmodulin and to the calmodulin-binding domains of myosin light chain kinases. To aid in recognizing this structural feature in sequences of peptides and proteins we have developed a computer algorithm which searches for sequences of appropriate length, hydrophobicity, helical hydrophobic moment, and charge to be considered as potential calmodulin-binding sequences. Such sequences occurred infrequently in proteins of known crystal structure. This algorithm was used to find the most likely site in the catalytic (gamma) subunit of phosphorylase b kinase for interaction with calmodulin (the delta subunit). A peptide corresponding to this site (residues 341-361 of the gamma subunit) was synthesized and found to bind calmodulin with approximately an 11 nM dissociation constant. A variant of this peptide in which an aspartic acid at position 7 in its sequence (347 of the gamma subunit) was replaced with an asparagine was found to bind calmodulin with approximately a 3 nM dissociation constant.
DeGrado
W F
WF
Central Research and Development Department, E.I. du Pont de Nemours and Company, Wilmington, Delaware 19898.
Erickson-Viitanen
S
S
Wolfe
H R
HR
O'Neil
K T
KT
D000465:Algorithms; D000595:Amino Acid Sequence; D001665:Binding Sites; D001667:Binding, Competitive; D002147:Calmodulin / Q000378:metabolism*; D002942:Circular Dichroism; D066298:In Vitro Techniques; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000378:metabolism; D010764:Phosphorylase Kinase / Q000378:metabolism*; D011487:Protein Conformation; D013050:Spectrometry, Fluorescence
D002147:Calmodulin; D010446:Peptide Fragments; D010764:Phosphorylase Kinase