ISSN:
1573-4919
Keywords:
rat heart
;
nuclei
;
phosphorylation
;
ATPase
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
Notes:
Abstract A nucleoside triphosphatase (NTPase) activity appeared to be associated with a highly purified nuclear preparation from rat cardiac ventricles. Different nucleoside triphosphates (UTP 〉 GTP 〉 ITP 〉 CTP) supported this enzymic activity, which was stimulated by Mg` but not by Call. The nuclear NTPase activity could be down regulated by endogenous phosphorylation of a 55,000 Mr protein. Maximal phosphorylation of the 55,000 Mr protein occurred in the presence of Mg2+-ATP. Addition of cAMP, cGMP, Ca2+, Ca2+/phospholipid, Ca2+/calmodulin, and catalytic subunit of cAMP-dependent protein kinase was not associated with any further phosphorylation of the 55,000 Mr protein. However, in the presence of Ca2+/calmodulin or the catalytic subunit of the cAMP-dependent protein kinase additional proteins became phosphorylated, but these had no effect on the Mg2+-NTPase activity. These results indicate that a protein with Mr 55,000 may be involved in the regulation the Mg2+-NTPase activity associated with rat cardiac nuclei.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00234574
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