PEST sequences do not influence substrate susceptibility to calpain proteolysis.
Mutations lowering the PEST score of domains surrounding the calmodulin (CaM)-binding region of the plasma membrane Ca(2+)-ATPase failed to influence the susceptibility of the enzyme to mu-calpain (mu-CANP). Synthetic peptides corresponding to the high PEST score C-terminal sequences A18 and B28 had no effect on the rate of pump proteolysis by mu-CANP, i.e. the peptides did not compete for a putative high PEST score recognition site for mu-CANP in the pump molecule. An accessible CaM-binding region appears to be critical for substrate (i.e. the Ca2+ pump) proteolysis and probably also for its recognition by mu-CANP; phosphorylation of the CaM-binding domain of the pump or its occupation by CaM significantly decreased the rate of proteolysis.
Institute of Biochemistry, Swiss Federal Institute of Technology, Zurich.
M
M
Molinari
J
J
Anagli
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E
Carafoli
D000595:Amino Acid Sequence; D001483:Base Sequence; D002118:Calcium / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D002147:Calmodulin / Q000378:metabolism; D002148:Calmodulin-Binding Proteins / Q000378:metabolism*; D002154:Calpain / Q000378:metabolism*; D017931:DNA Primers / Q000737:chemistry; D006801:Humans; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry; D013329:Structure-Activity Relationship; D013379:Substrate Specificity
D002147:Calmodulin; D002148:Calmodulin-Binding Proteins; D017931:DNA Primers; D010455:Peptides; D002154:Calpain; D000252:Calcium-Transporting ATPases; D002118:Calcium