This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
Function of phospholamban is 
Select and explain. 
A. Regulates Na+K+, B. Transports calcium out of mitochondria, C. Collects calcium into sarcoplasmic reticulum, D. Binds actin with myosin
C: Collects calcium into sarcoplasmic reticulum
Answer: C: Collects calcium into sarcoplasmic reticulum 
Explanation: Phospholamban increases the activity of SERCA
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It causes accumulation of Ca2+ by sarcoplasmic reticulum
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It leads to Lusiotropic effect, Increase in rate of relaxation