Mass of the postsynaptic density and enumeration of three key molecules
Mass of the postsynaptic density and enumeration of three key molecules
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DOI：
10.1073/pnas.0505359102
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发表时间：
2005-08-09
影响因子：
11.1
通讯作者：
Reese, TS
中科院分区：
文献类型：
--
作者：
Chen, XB;Vinade, L;Reese, TS
The total molecular mass of individual postsynaptic densities (PSDs) isolated from rat forebrain was measured by scanning transmission EM. PSDs had a mean diameter of 360 nm and molecular mass of 1.10 +/- 0.36 GDa. Because the mass represents the sum of the molecular masses of all of the molecules comprising a PSD, it becomes possible to derive the number of copies of each protein, once its relative mass contribution is known. Mass contributions of PSD-95, synapse-associated protein (SAP)97, and alpha-Ca2+/calmodulin-dependent protein kinase 11 (CaMKII) were determined by quantitative gel electrophoresis of PSD fractions. The number of PSD-95 molecules per average PSD, contributing 2.3% of the mass of the PSD, was calculated to be 300, whereas the number of SAP97 molecules, contributing 0.9% of the mass of the PSD, was 90. The alpha-CaMKII holoenzymes, which contribute 6% of the mass when brains are homogenized within 2 min of interrupting blood flow, have 80 holoenzymes associated with a typical PSD. When blood flow is interrupted 15 min before homogenization, the average mass of PSDs increases by approximate to 40%. The additional a-CaMKII associated with PSDs accounts for up to 20% of this mass increase, representing the addition of 100-200 alpha-CaMKII holoenzymes.
