Protein phosphorylation in the moulting gland of the crayfish,Orconectes limosus:Role of cyclic nucleotides, calcium, and moult inhibiting hormone (MIH)

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Abstract
Y-organs of the crayfish Orconectes limosus revealed a phosphorylation pattern which varied in different moulting stages. A 95-kDa-phosphoprotein increased in abundance as moulting proceeded, becoming the predominant phosphoprotein in stage D1. Phosphorylation of proteins with apparent molecular masses of 68 (pp68) and 17 kDa decreased during the moulting cycle. Phosphorylation of pp68 was evoked by incubating Y-organs of premoult animals with sinus gland extract. The presence of Ca2+ induced a decrease in overall kinase activity in Y-organ homogenates and also caused reduced phosphorylation of endogenous Y-organ proteins, most of them (200, 40, 31, and 17 kDa) exhibiting cAMP-dependent phosphorylation. cAMP-dependent phosphorylation of a 34- and 31-kDa-phosphoprotein (pp34, pp31) was detectable only in Y-organs of premoult animals. A 40-kDa-protein may be a substrate for an endogenous cGMP-dependent protein kinase since its phosphorylation can be stimulated by cGMP as well as cAMP.