Phosphorylation of protein components of isolated zymogen granule membranes from the rat pancreas

Lambert, Monique; Camus, Jean Claude; Christophe, Jean

doi:10.1016/0014-5793(74)80518-1

Cited by 22 publications

(2 citation statements)

References 7 publications

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“…Previous studies have demonstrated phosphorylation of several proteins in a membrane preparation of isolated zymogen granules, although the addition of cyclic AMP, the only intracellular messenger tested, did not consistently alter membrane protein phosphorylation (Lambert et al, 1974;Macdonald & Ronzio, 1974). Cyclic AMPactivated kinase activity was revealed, however, if exogenous substrate (histone) was used (Lambert et al, 1974;Lewis & Ronzio, 1979).…”

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confidence: 81%

Protein kinase activity associated with pancreatic zymogen granules

Burnham¹,

Munowitz²,

Thorn³

et al. 1985

Biochemical Journal

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Purified zymogen granules were prepared from rat pancreas by using an iso-osmotic Percoll gradient. In the presence of [gamma-32P]ATP, phosphorylation of several granule proteins was induced by Ca2+, most notably a Mr-13 000 protein, whereas addition of cyclic AMP was without effect. When phosphatidylserine was also added, Ca2+ increased the phosphorylation of additional proteins, with the largest effect on a protein of Mr 62 000. Purified granules were also able to phosphorylate exogenous substrates. Ca2+-induced phosphorylation of lysine-rich histone was enhanced over 3-fold in the presence of phosphatidylserine, and cyclic AMP-activated protein kinase activity was revealed with mixed histone as substrate. The concentrations of free Ca2+ and cyclic AMP required for half-maximal phosphorylation of both endogenous and exogenous proteins were 1-3 microM and 57 nM respectively. Treatment of granules with 0.25 M-KCl resulted in the release of phosphatidylserine-dependent kinase activity into a high-speed granule supernatant. In contrast, granule-protein substrates of Ca2+-activated kinase activity were resistant to KCl extraction, and in fact were present in purified granule membranes. Kinase activity activated by cyclic AMP was not extracted by KCl treatment. It is concluded that phosphorylation of integral membrane proteins in the zymogen granule can be induced by one or more Ca2+-activated protein kinases. Such a reaction is a potential mechanism by which exocytosis may be regulated in the exocrine pancreas by Ca2+-mediated secretagogues.

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confidence: 81%

Protein kinase activity associated with pancreatic zymogen granules

Burnham¹,

Munowitz²,

Thorn³

et al. 1985

Biochemical Journal

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“…Recently, considerable attention has been given to the phosphorylation of membrane proteins by endogenous protein kinases (Rubin & Rosen, 1975;Flosey & Tao, 1977). Such reactions have been described for plasma membranes isolated from a variety of sources: mammary gland (Majumder & Trukington, 1972), red blood cells (Avruch & Fairbanks, 1974;Guthrow et al, 1972; Rubin & Rosen, 1973;Hosey & Tao, 1976), fat cell (Chang et al, 1974), 3T3 cells (Mastro & Rozengurt, 1976)), rat liver microsomal membranes (Jergil & Ohlsson, 1974;Sharma et al, 1976;Sharma et al, 1978), chloroplast membrane (Bennett, 1977, pancreatic zymogen granules (MacDonald & Ronzio, 1974;Lambert et al, 1974), mitochondrial membranes (Moret et al, 1975), sarcoplasmic reticulum (Wray et al, 1973), muscle membrane (Andrew et al, 1975;Casnelle & Greengard, 1974;Andrew et al, 1973;Sulakhe & Drummond, 1974), and synaptic membranes (Ueda et al, 1973). Many of the above reactions exhibit cyclic nucleotide dependency (Guthrow et al, 1972;Rubin & Rosen, 1973;Chang et al, 1974;Lambert et al, 1974;Wray et al, 1973; Casnelle & Greengard, 1974; Sulakhe & Drummond, 1974;Ueda et al, 1973), while others do not (Majumder & Turkington, 1972; Mastro & Rozengurt, 1976;Sharma et al, 1976;MacDonald & Ronzio, 1974;Moret et al, 1975)…”

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confidence: 99%