Figure 5. Subcellular distribution of copine1 and its calcium-dependent association with membrane. NTM and GTM cells either untreated or treated with A23187 were fractionated into a total membrane fraction (Mem) and a whole cell lysate (Cyt) as described in the Methods section. Following SDS–PAGE and western blot, copine1 was detected using a mouse monoclonal copine1 antibody. Equal amounts of protein were loaded in each lane, and the protein content was determined using the Bradford method (Bio-Rad) and BSA as the standard. For the A23187-treated cells, Ca²⁺ and A23187 were incubated with TM cells for 30 min before cell collection. NTM: normal TM cells; GTM: glaucomatous TM cells. Data from the three experiments were averaged and graphed with error bars representing standard errors.