The Ca2+ affinity of the plasma membrane Ca2+ pump is controlled by alternative splicing.
The plasma membrane Ca2+ pump is a calmodulin-regulated P-type ATPase that is an essential element in controlling intracellular Ca2+ concentration. Studies on the gene structure of this pump have revealed an alternate splice option that changes the structure of the calmodulin-binding domain. This change in the structure of the enzyme results in a reduced calmodulin affinity. Tests of the enzyme's activity in the presence of a high calmodulin concentration, approximating that found inside living cells, show that this reduced calmodulin affinity causes a reduced apparent affinity of the enzyme for Ca2+. This shift in the Ca2+ activation occurs in a Ca2+ concentration range crucial to cellular function and is probably the physiologically important consequence of the alternate splice.
Enyedi
A
A
Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota 55905.
Verma
A K
AK
Heim
R
R
Adamo
H P
HP
Filoteo
A G
AG
Strehler
E E
EE
Penniston
J T
JT
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D006801:Humans; D008969:Molecular Sequence Data
D000252:Calcium-Transporting ATPases; D002118:Calcium