Xenbase is experiencing difficulties due to technical problems with the University of Calgary IT infrastructure and may go temporarily offline.

Click on this message to dismiss it.
Click here to close Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly. We suggest using a current version of Chrome, FireFox, or Safari.
Proc Natl Acad Sci U S A. March 26, 2013; 110 (13): 5163-8.

AMPA receptor/TARP stoichiometry visualized by single-molecule subunit counting.

Hastie P , Ulbrich MH , Wang HL , Arant RJ , Lau AG , Zhang Z , Isacoff EY , Chen L .

Members of the transmembrane AMPA receptor-regulatory protein (TARP) family modulate AMPA receptor (AMPA-R) trafficking and function. AMPA-Rs consist of four pore-forming subunits. Previous studies show that TARPs are an integral part of the AMPA-R complex, acting as accessory subunits for mature receptors in vivo. The TARP/AMPA-R stoichiometry was previously measured indirectly and found to be variable and dependent on TARP expression level, with at most four TARPs associated with each AMPA-R complex. Here, we use a single-molecule technique in live cells that selectively images proteins located in the plasma membrane to directly count the number of TARPs associated with each AMPA-R complex. Although individual GFP-tagged TARP subunits are observed as freely diffusing fluorescent spots on the surface of Xenopus laevis oocytes when expressed alone, coexpression with AMPA-R-mCherry immobilizes the stargazin-GFP spots at sites of AMPA-R-mCherry, consistent with complex formation. We determined the number of TARP molecules associated with each AMPA-R by counting bleaching steps for three different TARP family members: γ-2, γ-3, and γ-4. We confirm that the TARP/AMPA-R stoichiometry depends on TARP expression level and discover that the maximum number of TARPs per AMPA-R complex falls into two categories: up to four γ-2 or γ-3 subunits, but rarely above two for γ-4 subunit. This unexpected AMPA-R/TARP stoichiometry difference has important implications for the assembly and function of TARP/AMPA-R complexes.

PubMed ID: 23479622
PMC ID: PMC3612642
Article link: Proc Natl Acad Sci U S A.
Grant support: 1P50MH086403 NIMH NIH HHS, 1R01MH091193 NIMH NIH HHS, 2PN2EY018241 NEI NIH HHS , R01NS35549 NINDS NIH HHS , P50 MH086403 NIMH NIH HHS, R01 MH069792 NIMH NIH HHS, R01 MH091193 NIMH NIH HHS

Genes referenced: cacng2

My Xenbase: [ Log-in / Register ]
version: [3.11.2]

Major funding for Xenbase is provided by the National Institute of Child Health and Human Development, grant P41 HD064556