SERCA-Type of Calcium Pumps and Phospholamban

Re: Presentation 0237

Guoxiang Chu
chugg@email.uc.edu

On Mon Dec 14, Paul J. Bauer wrote
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>The hypothesis that PLB is most effective as a pentamer is interesting. However, even so PLB runs in SDS-PAGE as pentamer, �can you really exclude that the physiologically active PLB is some fraction of monomeric PLB which co-exists in thermodynamic equilibrium with the pentameric aggregates?

Dear Dr. Bauer:

We agree that monomeric PLB is also active in inhibiting the SERCA2 affinity. �However, based on our transgenic mouse studies, the pentameric form appears to be more "functionally active" than monomeric PLB. �An inherent problem in all these studies is the use of SDS-PAGE to assign a molecular weight for the wild-type/mutant PLB and this may not reflect the in vivo state of the protein in native SR membranes.

Litsa Kranias

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