Murtazina, D.A., Petukhov, S.P., Storey, K.B., Rubtsov, A.M., and Lopina, O.D.
A 100-kDa protein that is a main component of the microsomal fraction fromrabbit gastric mucosa is phosphorylated by cAMP-dependent protein kinase (PKA) in the presence of 0.2% Triton X-100. Microsomes from rabbit gastric mucosa possess activity of H,K-ATPase but not activity of Na,K-ATPase. Incubation of microsomes with 5 ÁM fluorescein 5'-isothiocyanate (FITC) results in both an inhibition of H,K-ATPase and labeling of a protein with an electrophoretic mobility corresponding to the mobility of the protein phosphorylated by PKA. The data suggest that the alpha-subunit of H,K-ATPase can be a potential target for PKA phosphorylation.