A cluster of basic amino acid residues in calcineurin b participates in the binding of calcineurin to phosphatidylserine vesicles.
Interactions between phospholipid membranes and the acyl chain and specific amino acid residues of myristoylated proteins are necessary for membrane association. In the present study we tested the effects of mutations of calcineurin B subunit amino acid residues K(20)K(21), K(24)R(25), K(27)K(28) to Glu on the interactions between calcineurin and phosphatidylserine vesicles. Calcineurin-phosphatidylserine interactions were measured using binding assays and assays of phosphatidylserine-stimulated calcineurin phosphatase activity. The reverse-charge calcineurin B subunit mutant had a slower mobility in SDS-PAGE relative to wild-type calcineurin B. In addition, the myristoylated calcineurin B reverse-charge mutant had a slower mobility in SDS-PAGE compared to the non-myristoylated form, in contrast to the faster mobility of myristoylated wild-type calcineurin B relative to non-myristoylated calcineurin B. The reverse-charge mutations had no apparent effect on N-terminal myristoylation, Ca(2+)-binding, or calcineurin heterodimer formation and stimulation of Ca(2+)/calmodulin-dependent phosphatase activity. However, in contrast to the results obtained using native calcineurin, phosphatidylserine vesicles did not bind to or activate the phosphatase activity of calcineurin containing the calcineurin B reverse-charge mutant. These results indicate that calcineurin B contains an amino terminal basic residue cluster that is involved in the binding of calcineurin to acidic phospholipids.
Martin
B A
BA
Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA.
Oxhorn
B C
BC
Rossow
C R
CR
Perrino
B A
BA
D000596:Amino Acids / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites; D001921:Brain / Q000378:metabolism; D019703:Calcineurin / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D002118:Calcium / Q000737:chemistry / Q000378:metabolism; D002147:Calmodulin / Q000737:chemistry / Q000378:metabolism; D002417:Cattle; D066298:In Vitro Techniques; D009154:Mutation / Q000235:genetics* / Q000502:physiology; D009227:Myristic Acids / Q000737:chemistry; D010718:Phosphatidylserines / Q000737:chemistry / Q000378:metabolism*; D010743:Phospholipids / Q000737:chemistry / Q000378:metabolism*; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D021122:Protein Subunits; D051381:Rats; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism
D000596:Amino Acids; D002147:Calmodulin; D009227:Myristic Acids; D010718:Phosphatidylserines; D010743:Phospholipids; D021122:Protein Subunits; D011994:Recombinant Proteins; C120817:calcineurin phosphatase; D019703:Calcineurin; D010744:Phosphoric Monoester Hydrolases; D002118:Calcium