The Plasma Membrane Ca2+-ATPase Isoform 4 Is Localized in Lipid Rafts of Cerebellum Synaptic Plasma Membranes

Abstract

Here we describe the association of the synaptosomal plasma membrane Ca 2؉ -ATPase (PMCA) from pig cerebellum with cholesterol/sphingomyelin-rich membrane domains (rafts). The PMCA4 was localized exclusively in rafts prepared by floatation in Nycodenz density gradients of ice-cold Brij 96 extracts. This was corroborated by its colocalization with the raft markers cholesterol, ganglioside GM1, and PrP C . The remaining PMCA isoforms were found in the detergent-soluble fractions, with the majority of the membrane proteins. Activity assays confirmed the bimodal distribution of the PMCA isoforms in the density gradient, with a lower activity for PMCA4 and greater stimulation by calmodulin than for the other isoforms. By providing an ordered membrane microenvironment, lipid rafts may contribute to the interaction of PMCA4 with proteins involved in Ca 2؉ signaling at discrete functional positions on the synaptic nerve terminals.

Activation of Adenosine A2A Receptors Induces TrkB Translocation and Increases BDNF-Mediated Phospho-TrkB Localization in Lipid Rafts: Implications for Neuromodulation

“…Cholesterol content from the gradient fractions was analyzed using a colorimetric assay (Sepú lveda et al, 2006) with minor modifications. Briefly, lipids were extracted by mixing 200 l of samples from each gradient fraction with 1 ml of chloroform/methanol (2:1), transferred to a glass tube and dried under nitrogen.…”

Isoform-specific up-regulation of plasma membrane Ca2+ATPase expression during colon and gastric cancer cell differentiation

“…PMCA4 has also been observed to display a polarized expression pattern in kidney epithelial cells [81], and to communicate with mitochondria located in close proximity to the plasma membrane [82]. Finally, PMCA4 has recently been published to be specifically associated with lipid rafts in synaptic plasma membranes [83], whereas the PMCA1, 2 and 3 proteins were found in other membrane domains. Taken together these observations show, that despite their shared basic biochemical activity (i.e.…”

The Homer-1 protein Ania-3 interacts with the plasma membrane calcium pump

“…The PMCAs are calmodulin-regulated enzymes that are essential for maintaining low intracellular calcium concentrations in the living cell [30,31]. Recent work has shown that PMCA isoforms and splice variants are active participants in localized Ca 2+ signaling, and that their targeting to and abundance at defined membrane sites must therefore be closely regulated [32][33][34][35]. All PMCA isoforms are expressed in the brain, with PMCA2 being abundant in several regions including the cerebellum, forebrain and hippocampus [28,36].…”