Actin molecular weight

G-actin (globular actin) has a molecular weight of about 42 kDa. In higher vertebrates, six isoforms of G-actin, which contain 374/375 residues, are expressed in a cell-specific manner. They are present in striated muscle cells (skeletal and cardiac isoforms), smooth muscle cells (vascular and visceral isoforms) and in non-muscle cells (two isoforms). 

Carlsson, L., Nystrom, L.E., Sundkvist, 1.. Markey. F.. Lindberg, U. (1977). Actin polymerizability is influenced by profilin, a low molecular weight protein in non-muscle cells. J. Mol. Biol. 115, 465-483. 

Since the molecular weight of GAPDH is around 36 kDa and P-actin is about 42 kDa, their bands appear in distinct areas of the membrane and are unlikely to interfere with each other. However if the two or more proteins to be detected on the same membrane have a similar molecular weight, stripping and re-probing are necessary (see Note 15). 

Cross-linked PVP can also be obtained by cross-linking tire preformed polymer chemically (with persulfates, hydrazine, or peroxides) or with actinic radiation. If the starting PVP homopolymer is too low in molecular weight or too dilute, cyclization or cleavage is preferred. 

Pollard, T. D. (1984). Purification of a high molecular weight actin filament gelation protein from Acanthamoeba that shares antigenic determinants with vertebrate spectrins. /. Cell Biol. 99, 1970-1980. 

Actin. Rabbit muscle G-actin is globular with a molecular weight of 4.2 X 104. In the presence of salts it is polymerized into F-action (34). The principal properties of fish actin (35-37,40, 43,44), including amino acid composition (41), are similar to rabbit actin, but fish actin is more readily extracted from wet muscle by salt solutions as a viscous solution of actomyosin (22,35,36,45). 

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