Comparison of SERCA1a Calcium Pumps Before and After Phosphorylation



Reset view of E1 SERCA1a.

Reset view of E2 SERCA1a.

Highlight the calcium ions (green) in the E1 structure (not available in E2 structure since this form has released calcium to the lumen of the SER).


In the E1 structure, highlight transmembrane domains with M1-M10 in blue except M1 is brown and M3 is red.

Compare the transmembrane domains for the E2 structure with M1-M10 in blue except M1 is brown and M3 is red. Note the difference in the angles of M1 and M3.


Now focus on M4 and M5 with M1 (brown), M3 (red), M4 (purple), M5 (orange) and all others blue. Slab mode has been turned on so you can see M4 and M5 more clearly.

Compare the same regions in the E2 state with M1 (brown), M3 (red), M4 (purple), M5 (orange) and all others blue. Slab mode has been turned on so you can see M4 and M5 more clearly.


Now zoom out and look at the two large cytoplasmic domains in the E1 state. The smaller cytoplasmic loop is called the "A domain" (purple) and is composed of amino acids 125-245. The larger cytoplasmic domain (red) is where ATP binds and the enzyme is phosphorylated (yellow). This larger domain is composed of amino acids 335-750.

Compare the same cytoplasmic domains in the E2 state. The red domain binds ATP and Asp 351 (yellow) is phosphorylated. The "A domain" (purple) rotates by about 110 degrees horizontally.

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© Copyright 2003 Department of Biology, Davidson College, Davidson, NC 28035
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