| Title: |
Mpp4 is required for proper localization of plasma membrane calcium ATPases and maintenance of calcium homeostasis at the rod photoreceptor synaptic terminals |
| Authors: |
Yang, Jun; Pawlyk, Basil; Wen, Xiao-Hong; Adamian, Michael; Soloviev, Maria; Michaud, Norman; Zhao, Yun; Sandberg, Michael A.; Makino, Clint L.; Li, Tiansen |
| Publisher Information: |
Oxford University Press |
| Publication Year: |
2007 |
| Collection: |
HighWire Press (Stanford University) |
| Subject Terms: |
ARTICLES |
| Description: |
Membrane palmitoylated protein 4 (Mpp4) is a member of the membrane-associated guanylate kinase family. We show that Mpp4 localizes specifically to the plasma membrane of photoreceptor synaptic terminals. Plasma membrane Ca2+ ATPases (PMCAs), the Ca2+ extrusion pumps, interact with an Mpp4-dependent presynaptic membrane protein complex that includes Veli3 and PSD95. In mice lacking Mpp4, PMCAs were lost from rod photoreceptor presynaptic membranes. Synaptic ribbons were enlarged, a phenomenon known to correlate with higher Ca2+. SERCA2 (sarcoplasmic-endoplasmic reticulum Ca2+ ATPase, type 2), which pumps cytosolic Ca2+ into intracellular Ca2+ stores and localizes next to the ribbons, was increased. The distribution of IP 3 RII (InsP 3 receptor, type 2), which releases Ca2+ from the stores, was shifted away from the synaptic terminals. Synaptic transmission to second-order neurons was maintained but was reduced in amplitude. These data suggest that loss of Mpp4 disrupts a Ca2+ extrusion mechanism at the presynaptic membranes, with ensuing adaptive responses by the photoreceptor to restore Ca2+ homeostasis. We propose that Mpp4 organizes a presynaptic protein complex that includes PMCAs and has a role in modulating Ca2+ homeostasis and synaptic transmission in rod photoreceptors. |
| Document Type: |
text |
| File Description: |
text/html |
| Language: |
English |
| Relation: |
http://hmg.oxfordjournals.org/cgi/content/short/16/9/1017; http://dx.doi.org/10.1093/hmg/ddm047 |
| DOI: |
10.1093/hmg/ddm047 |
| Availability: |
http://hmg.oxfordjournals.org/cgi/content/short/16/9/1017; https://doi.org/10.1093/hmg/ddm047 |
| Rights: |
Copyright (C) 2007, Oxford University Press |
| Accession Number: |
edsbas.3462C00F |
| Database: |
BASE |