1. Academic Validation
  2. SAP102 is a highly mobile MAGUK in spines

SAP102 is a highly mobile MAGUK in spines

  • J Neurosci. 2010 Mar 31;30(13):4757-66. doi: 10.1523/JNEUROSCI.6108-09.2010.
Chan-Ying Zheng 1 Ronald S Petralia Ya-Xian Wang Bechara Kachar Robert J Wenthold
Affiliations

Affiliation

  • 1 Laboratories of Neurochemistry and Cell Structure and Dynamics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland 20892, USA. zhengchan@nidcd.nih.gov
Abstract

Membrane-associated guanylate kinases (MAGUKs), which are essential proteins in the postsynaptic density (PSD), cluster and anchor glutamate receptors and Other proteins at synapses. The MAGUK family includes PSD-95, PSD-93, SAP102, and SAP97. Individual family members can compensate for one another in their ability to recruit and retain receptors at the postsynaptic membrane as shown through deletion and knock-down studies. SAP102 is highly expressed in both young and mature neurons; however, little is known about its localization and mobility at synapses. Here, we compared the distribution, mobility, and turnover times of SAP102 to the well studied MAGUK PSD-95. Using light and electron microscopy, we found that SAP102 shows a broader distribution as well as peak localization further away from the postsynaptic membrane than PSD-95. Using fluorescence recovery after photobleaching (FRAP), we found that 80% of SAP102 and 36% of PSD-95 are mobile in spines. Previous studies showed that PSD-95 was stabilized at the PSD by N-terminal palmitoylation. We found that stabilization of SAP102 at the PSD was dependent on its SH3/GK domains but not its PDZ interactions. Furthermore, we showed that stabilizing actin or blocking NMDA/AMPA receptors reduced the mobile pool of SAP102 but did not affect the mobile pool of PSD-95. Our results show significant differences in the localization, binding mechanism, and mobility of SAP102 and PSD-95. These differences and the compensatory properties of the MAGUKs point out an unrecognized versatility of the MAGUKs in their function in synaptic organization and plasticity.

Figures