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. Author manuscript; available in PMC: 2017 Aug 1.
Published in final edited form as: Biochim Biophys Acta. 2016 Feb 24;1861(8 Pt B):862–873. doi: 10.1016/j.bbalip.2016.02.015

Figure 1.

Figure 1

Models of the PI cycle and SOCE.

(A) An illustration of the first PI cycle model proposed by Mabel and Lowell Hokin in 1964. © Michell and BBA, 1975. Originally published in Biochim Biophys Acta, 415 (1975) 81-147.

(B) An advanced version of the PI cycle model proposed by Robert Michell in 1975. The ideas that the PI cycle is an inter-organelle pathway and that cytosolic exchange proteins mediate PI/PA shuttling between the ER and the PM were incorporated into this model. © Michell and BBA, 1975. Originally published in Biochim Biophys Acta, 415 (1975) 81-147.

(C) The first model of SOCE proposed by James Putney in 1986. Ag, agonist; RA, receptor; PIP2, PI(4,5)P2; (1,4,5)IP3, IP3; RI, IP3R. © Putney and Cell Calcium, 1986. Originally published in Cell Calcium, 7 (1986) 1-12.

(D) A revised model of SOCE proposed by James Putney in 1990. The dashed arrow indicates an unknown mechanism that links ER Ca2+ depletion to the opening of a Ca2+ channel at the PM. Ca2+ first enters the cytosol and is then pumped into the ER lumen to refill the ER Ca2+ store. R, receptor; GP; G-protein. © Putney and Cell Calcium, 1990. Originally published in Cell Calcium, 11 (1990) 611-624.