Activation (maturation) of frog oocytes is signaled through a MAP kinase signaling

Chapter 0, Problem 15-14

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Activation (maturation) of frog oocytes is signaled through a MAP kinase signaling module. An increase in the hormone progesterone triggers the module by stimulating the translation of Mos mRNA, which is the frogs MAP kinase kinase kinase (Figure Q152). Maturation is easy to score visually by the presence of a white spot in the middle of the brown surface of the oocyte (see Figure Q152). To determine the doseresponse curve for progesterone-induced activation of MAP kinase, you place 16 oocytes in each of six plastic dishes and add various concentrations of progesterone. After an overnight incubation, you crush the oocytes, prepare an extract, and determine the state of MAP kinase phosphorylation (hence, activation) by SDS polyacrylamide-gel electrophoresis (Figure Q153A). This analysis shows a graded response of MAP kinase to increasing concentrations of progesterone.