17.2 The mating pathway is triggered by signal transduction Mammal Yea st Extr acellular e:Mer Polypeptid Mem brane eceptor Cy colic sem- 5 com ponents ctivates inactivates SOS GAP1 ST E23(GBr) Ras ST ↓要 ST E11 C-Raf STE5 MEK D MAP kinase US3 KSS1 N dear campton 2: Y'an pointe t ef rectors an scission As Figure 26.29 Homologous proteins are found in signal transduction cascades in a wide variety of organisms 请莘大Figure 26.29 Homologous proteins are found in signal transduction cascades in a wide variety of organisms. 17.2 The mating pathway is triggered by signal transduction