Fig. 4. Influence of the complementary mating type pheromone, gamone 2, on the expression of gamone 1. (A) The transcriptional level of gamone 1 was examined by northern blotting of the moderately starved cells of both types stimulated with gamone 2 (+G2) or unstimulated (–G2). Total RNA was prepared from each cell type (6 µg/lane). The level of the transcription of gamone 1 was increased when starved type I cells were stimulated with gamone 2. Type II cells did not transcribe gamone 1 mRNA, irrespective of the presence of gamone 2. The graph shows the relative amounts of gamone 1 mRNA. (B) The secreted mature gamone 1 protein was detected by SDS-PAGE and silver staining. (C) The biological activity of secreted mature gamone 1 was measured and is represented by the index of pair formation.