Step I Ca-ATPase located where?

[ChessMaster3000]

It looks like ca-atpase in muscle cells can be both on the sarcolemmal membrane and plasma membrane. For the purposes of step 1, should we consider them to be only on the sarcoplasmic reticulum membrane?

 

[NeuroLAX]

SERCA is obviously found in muscle cells, but isn't PMCA ubiquitous?

 

[ulikedaggers]

It looks like ca-atpase in muscle cells can be both on the sarcolemmal membrane and plasma membrane. For the purposes of step 1, should we consider them to be only on the sarcoplasmic reticulum membrane?

The sarcolemma is the plasma membrane of a muscle cell. I don't think skeletal muscles have a plasma membrane calcium pump. All of the calcium used in skeletal muscle contraction comes from the SR (unlike cardiac and smooth that utilize extracellular calcium too).

If skeletal muscle had PM calcium pumps, nifedipine and verapamil would reduce their contractility.

 

[ChessMaster3000]

The sarcolemma is the plasma membrane of a muscle cell. I don't think skeletal muscles have a plasma membrane calcium pump. All of the calcium used in skeletal muscle contraction comes from the SR (unlike cardiac and smooth that utilize extracellular calcium too).

If skeletal muscle had PM calcium pumps, nifedipine and verapamil would reduce their contractility.

I suppose i was referring to cardiac and smooth muscle Ca-ATPase pumps.

@NeuroLAX exactly. So unless they refer to it as SERCA, the generic term "ca-atpase" could refer to the plasma membrane or serca, right?