ISSN:
0730-2312
Schlagwort(e):
polyamines
;
cyclic-AMP-dependent protein kinase
;
calcium/phospholipid-dependent protein kinase C
;
messenger-independent protein kinase
;
ornithine decarboxylase
;
rat thyroid
;
Life and Medical Sciences
;
Cell & Developmental Biology
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Biologie
,
Chemie und Pharmazie
,
Medizin
Notizen:
Ornithine decarboxylase, the rate-limiting enzyme in polyamine biosynthesis, has been shown to be regulated in thyroid by thyrotropin both in vivo and in vitro. Little, however, is known of the role of polyamines in thyroid cell function. Since studies in other tissues suggest that polyamines may influence protein phosphorylation, we studied the effect of the polyamines on various protein kinase activities in rat thyroid. Putrescine, spermidine, and spermine inhibit cyclic-AMP-dependent histone H1 kinase activity when measured in the cytosol fraction of rat thyroid; this effect is largely reproduced by NaCl concentrations of equivalent ionic strength. Both spermidine and spermine effect a 1.6-2.4-fold increase in cytosolic cyclic-AMP-independent (messenger-independent) casein kinase activity; stimulation by both polyamines is maximal at 5mM. A similar profile of stimulation is observed for messenger-independent casein kinase activity in crude nuclear preparations. Sodium chloride fails to stimulate both cytosolic and nuclear messenger-independent casein kinase activities at ionic strength equivalent to the spermine concentrations used. Spermine, but not putrescine, spermidine, or sodium chloride, inhibits calcium/phospholipid-dependent protein kinase C activity in cytosol extracts partially purified by DEAE chromatography. These findings suggest that regulation of protein kinase(s) by polyamines may represent a proximal locus (i) of action of thyrotropin-regulated ornithine decarboxylase activity in thyroid.
Zusätzliches Material:
4 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/jcb.240280408
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