Sarco/endoplasmic-reticulum calcium ATPase SERCA1 is maintained in the endoplasmic reticulum by a retrieval signal located between residues 1 and 211.
The location of sarco/endoplasmic-reticulum calcium ATPase (SERCA) retention/retrieval motifs in the sequence of the SERCA1 has been investigated by examining the subcellular location in COS-7 cells of enhanced-green-fluorescent-protein-tagged calcium-pump chimaeras. These chimaeras have been constructed from the fast-twitch SERCA1 and the plasma-membrane calcium ATPase PMCA3. The N-terminal, central and C-terminal segments of these calcium pumps were exchanged between SERCA1 and PMCA3. The segments exchanged correspond to residues 1-211, 212-711 and 712-994 of SERCA1, and residues 1-264, 265-788 and 789-1159 of PMCA3 respectively. Only chimaeras containing the N-terminal segment of SERCA1 were located in the endoplasmic reticulum (ER), whereas chimaeras containing the N-terminal segment from PMCA3 were able to escape from the ER and enter the endomembrane pathway en route for the plasma membrane. Co-localization of SERCA1 in COS-7 cells with the ER/Golgi-intermediate compartment marker ERGIC53 indicates that SERCA1 is maintained in the ER by a process of retrieval. These results indicate that the N-terminal region of SERCA1, containing transmembrane helices M1 and M2, contains an ER-retrieval signal.
Newton
Thomas
T
Division of Biochemistry and Molecular Biology, School of Biological Sciences, University of Southampton, Southampton SO16 7PX, UK.
Black
John P J
JP
Butler
John
J
Lee
Anthony G
AG
Chad
John
J
East
J Malcolm
JM
D000818:Animals; D019556:COS Cells; D000252:Calcium-Transporting ATPases / Q000737:chemistry / Q000378:metabolism*; D027682:Cation Transport Proteins; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D053499:Plasma Membrane Calcium-Transporting ATPases; D011485:Protein Binding; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D015398:Signal Transduction; D013347:Subcellular Fractions / Q000378:metabolism
D027682:Cation Transport Proteins; D053499:Plasma Membrane Calcium-Transporting ATPases; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D000252:Calcium-Transporting ATPases