ACTIN - A TARGET OF LIPOPOLYSACCHARIDE-INDUCED PHOSPHORYLATION IN HUMAN MONOCYTES

We have previously reported that lipopolysaccharide (LPS) causes alter ed phosphate labelling of cytosolic proteins of 36 kDa and 38 kDa (p36 /38) and that inhibition of phosphorylation is accompanied by a loss o f cytokine production. Here we have purified the two phosphorylated pr oteins via two-dimensional polyacrylamide gel electrophoresis. P 36 wa s found to consist of two proteins p36a and p36b. The proteins were an alysed by matrix-assisted laser desorption ionization (MALDI) mass spe ctrometry and p36b was identified as gamma-actin, p36a as beta/gamma-a ctin. The ability of LPS to cause altered phosphate labelling of beta/ gamma-actin suggests a participation of the microfilament network in L PS-induced monocyte activation. (C) 1997 Academic Press.