Abstract
Western blot analysis is a commonly utilized technique for determining specific protein levelsin clinical samples. For normalization of protein levels in Western blot, a suitable loadingcontrol is required. On account of its relatively high and constant expression, β-actin has beenwidely employed in Western blot of cell cultures and tissue extracts. However, β-actin'spresence in human plasma and this protein's putative role as a plasma-based loading controlfor Western blot analysis remain unknown. In this study,anenzymelinkedimmunosorbentassaywasusedtodeterminetheconcentration of β-actin in human plasma, which is 6.29 ±0.54 ng/ml. In addition, the linearity of β-actin immunostaining and loaded protein amountwas evaluated by Western blot, and a fine linearity (R2=0.974 ± 0.012) was observed.Furthermore, the expression of plasma β-actin in major depressive disorder subjects andhealthy controls was compared. The data revealed no statistically significant differencebetween these two groups. Moreover, the total coefficient of variation for β-actin expressionin the two groups was 9.2 ± 1.2%. These findings demonstrate that β-actin is present inhuman plasma and may possibly be used as a suitable loading control for plasma-basedWestern blot analysis in major depressive disorder.
Key words: β-actin; loading control; Western blot; major depressive disorder; plasma