Approximately 90% of the Chlamydomonas reinhardtii chloroplast and cytoplasmic rRNAs was transcribed in the nuclear G1 phase, which occurred during the light period under an alternating light-dark synchronization regime of 12 h each. The remaining 10% of chloroplast and cytoplasmic rRNAs was transcribed from its respective DNAs in the dark period, in the midst of an apparent turnover of a trans...

The site specificity of tyrosine hydroxylase phosphorylation in intact PC12 cells, labeled with 32Pi, was investigated. Digestion of 32P-tyrosine hydroxylase with trypsin produced five distinct 32P-labeled peptides (termed PC-1 through PC-5). Sequencing of the peptides revealed four acceptor sites: Ser8, Ser19, Ser31, and Ser40. The phosphorylation site in peptides PC-1 (AV-SEQDAK) and PC-2 (RA...

High specific activity [beta-32P]ATP and [beta-32P]CTP were used to study in vitro transcriptional initiation and subsequent capping of simian virus 40 (SV40) early and later RNAs. More than 40% of the capped SV40 RNA synthesized in vitro was also polyadenylylated. With [beta-32P]ATP, only adenosine-containing caps were labeled and the incorporated radioactive phosphate was found exclusively in...

Small GTPases of the Ypt/rab family are involved in the regulation of vesicular transport. These GTPases apparently function during the targeting of vesicles to the acceptor compartment. Two members of the Ypt/rab family, Ypt1p and Sec4p, have been shown to regulate early and late steps of the yeast exocytic pathway, respectively. Here we tested the role of two newly identified GTPases, Ypt31p ...

Rat liver nuclei were isolated and sonicated for extraction in order to study the capping of RNA. The guanosine 7-methyltransferase was purified from the extract by hydroxylapatite column chromatography with stepwise addition of phosphate buffer. It was assayed by using as methyl acceptor synthetic G(5')ppp(5')G and S-adenosylmethionine as donor. The enzyme appeared in a sharp peak at 160 mM. T...

The hydrolysis of glycerophospholipids in very low density lipoprotein by enzyme(s) released into circulation after the injection of heparin to rats was studied. [32P]Lysolecithin was formed rapidly from [32P]lecithin when very low density lipoprotein, labeled biosynthetically with 32P, was incubated with postheparin plasma. The [32P]lysolecithin was associated with the plasma protein fraction ...

Thrombin-induced aggregation and serotonin release were markedly enhanced in platelets from spontaneously hypertensive rats (SHR) when compared with those from normotensive Wistar-Kyoto rats (WKY). Since phosphoinositides are involved in calcium-mediated platelet responses, the metabolism of these lipids was investigated in SHR and WKY by using 32P-labeled quiescent platelets. In unstimulated c...