Identification of two 17-kDa rat parotid gland phosphoproteins, subjects for dephosphorylation upon beta-adrenergic stimulation, as destrin- and cofilin-like proteins.
We previously reported that when 32Pi-loaded rat parotid slices are incubated with the beta-adrenergic agonist isoproterenol, the level of a soluble 32P-labeled 17-kDa protein (pp17) decreases rapidly (Kanamori, T., and Hayakawa, T. (1982) Biochem. Int. 4, 517-523). Here we show that pp17 consists of two distinct phosphoproteins (pp17a and pp17b), identify their unphosphorylated forms (p17a and p17b, respectively), and provide evidence for their beta-adrenergic stimulation-induced dephosphorylation. Since p17a and p17b were predominant forms even in nonstimulated cells, peptides were generated from them with Staphylococcus aureus V8 protease or cyanogen bromide; subsequent sequencing of these peptides and homology search allowed identification of p17a and p17b as destrin- and cofilin-like proteins, respectively. Interestingly, they were also dephosphorylated in response to cholinergic stimulation. Because destrin and cofilin are actin-depolymerizing proteins whose activities are possibly regulated by their phosphorylation/dephosphorylation, the two parotid proteins reported here might be involved in cortical F-actin disruption observed in parallel with exocytotic amylase secretion.
Kanamori
T
T
Department of Biochemistry, School of Dentistry, Aichi-Gakuin University, Nagoya, Japan.
Hayakawa
T
T
Suzuki
M
M
Titani
K
K
D051339:Actin Depolymerizing Factors; D000595:Amino Acid Sequence; D000681:Amylases / Q000378:metabolism; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism; D003598:Cytoskeletal Proteins; D051345:Destrin; D066298:In Vitro Techniques; D008840:Microfilament Proteins; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000378:metabolism; D010306:Parotid Gland / Q000201:enzymology / Q000378:metabolism*; D010750:Phosphoproteins / Q000302:isolation & purification / Q000378:metabolism*; D010766:Phosphorylation; D051381:Rats; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D016415:Sequence Alignment
D051339:Actin Depolymerizing Factors; D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; D051345:Destrin; D008840:Microfilament Proteins; D009419:Nerve Tissue Proteins; D010750:Phosphoproteins; D011943:Receptors, Adrenergic, beta; D000681:Amylases