Interaction of [125I] beta nerve growth factor with acidic proteins.

We have demonstrated that the beta nerve growth factor will interact with various acidic proteins apparently nonspecifically. When 125I-labeled beta nerve growth factor at a concentration of 3.8 X 10(-10) M is incubated with an acidic protein at 2 mg/ml (4.5 X 10(-6)-4.4 X 10(-5) M), a complex is formed. This complex changes the isoelectric point of the 125I-labeled beta nerve growth factor sufficiently so that the 125I-labeled beta nerve growth factor migrates anomalously in polyacrylamide gel electrophoresis. The interaction between beta nerve growth factor and bovine serum albumin, which appears to be complex, may be the cause of the previously reported activation of the beta nerve growth factor when bovine serum albumin is present in a typical bioassay.