Number of alpha-CaMKII holoenzyme in Post Synaptic Density (PSD)

Range ≈80 enzymes
Organism Rat Rattus norvegicus
Reference Chen X, Vinade L, Leapman RD, et al. Mass of the postsynaptic density and enumeration of three key molecules. Proceedings of the National Academy of Sciences of the United States of America. 2005 102(32):11551-11556. doi:10.1073/pnas.0505359102 p.11555 left column 3rd paragraphPubMed ID16061821
Method Abstract: "The total molecular mass of individual postsynaptic densities (PSDs) isolated from rat forebrain was measured by scanning transmission EM (electron microscopy)... 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."
Comments P.11555 left column 3rd paragraph: "In the 2-min and 15-min unpurified PSD fractions, the total mass contributions of CaMKII were ≈10.4% and ≈19.4% of the PSD mass, respectively, and the mass contribution of CaMKII clusters to PSDs, estimated by EM planimetry measurements, were ≈4.3% and ≈10.7%, respectively. The latter figure is in good agreement with the results with CO2 PSDs. Therefore, the ultimate mass contribution of CaMKII to the mass of PSDs in the 2- and 15-min fractions is ≈6.1% and 8.7%, respectively, making the number of α-CaMKII holoenzymes per PSD ≈80 in 2-min PSD and ≈170 in 15-min PSDs (Table 2, P < 0.04, Student's t test). These measurements imply that ≈41% and ≈55% of the total α-CaMKII in the fraction is sequestered in CaMKII clusters in the 2-min and 15-min PSD fractions, respectively."
Entered by Monsoon Man
ID 114329