Presence of diadenosine 5',5'''-P/sup 1/,P/sup 4/-tetraphosphate (Ap/sub 4/A) in mammalian cells in levels varying widely with proliferative activity of the tissue: a possible positive pleiotypic activator

Journal Article · Mon Nov 01 04:00:00 EST 1976 · Proc. Natl. Acad. Sci. U.S.A.; (United States)

DOI:https://doi.org/10.1073/pnas.73.11.3984· OSTI ID:7122417

Rapaport, E; Zamecnik, P C

An accurate assay of diadenosine 5',5'''-P/sup 1/,P/sup 4/-tetraphosphate (A(5') pppp(5')A), which was shown to be formed in vitro in the backreaction of the amino acid activation step, has been developed in various cell lines in culture and in normal mouse liver or hepatoma in vivo. Use of radioactive labeling of acid-soluble nucleotides to high specific activity followed by chromatographic separation techniques yielded levels of Ap/sub 4/A varying from 5 to 0.05 ..mu..M (from 30 pmol/mg of protein to 0.15 pmol), depending on the doubling time of the cell line or the proliferative state of the cells. The levels of Ap/sub 4/A in cells is inversely related to their doubling time, varying from 0.1 x 10/sup -4/ of the cellular ATP levels in slowly growing cells to 20 x 10/sup -4/ of the ATP levels of cells with rapid doubling times. The steady-state levels of ATP of different cell lines, although showing some fluctuations, are not related to the doubling time of the cells. Arrest of cellular proliferation by serum deprivation or amino acid starvation, which does not alter the cellular ATP levels more than 2-fold, does nevertheless cause a decrease of 30- to 50-fold in the Ap/sub 4/A levels. Inhibition of protein synthesis by pactamycin or puromycin or inhibition of DNA synthesis by hydroxyurea leads to a more dramatic decrease of 50- to 100-fold in intracellular Ap/sub 4/A levels. The metabolic lability of Ap/sub 4/A is also demonstrated by its rapid depletion after decreases in the ATP/ADP ratio. The possibility of Ap/sub 4/A being a metabolic ''signal nucleotide'' that is formed at the onset of protein synthesis and is active in positive growth regulation (positive pleiotypic activation) is discussed.

• Research Organization: Huntington Memorial Hospital, Boston
• OSTI ID: 7122417
• Journal Information: Proc. Natl. Acad. Sci. U.S.A.; (United States), Journal Name: Proc. Natl. Acad. Sci. U.S.A.; (United States) Vol. 73:11; ISSN PNASA
• Country of Publication: United States
• Language: English

Related Subjects

550200* -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
ADENOSINE
AMIDES
ANIMAL CELLS
ANIMALS
ANTIBIOTICS
ATP
BIOASSAY
BIOLOGICAL EFFECTS
BIOSYNTHESIS
BODY
CELL CULTURES
CELL PROLIFERATION
CHROMATOGRAPHY
DIGESTIVE SYSTEM
DISEASES
DNA
DRUGS
GLANDS
HEPATOMAS
HYDROXY COMPOUNDS
HYDROXYUREA
LIVER
MAMMALS
MICE
NEOPLASMS
NUCLEIC ACIDS
NUCLEOSIDES
NUCLEOTIDES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
OXYGEN COMPOUNDS
PHOSPHATES
PHOSPHORUS COMPOUNDS
PROTEINS
PUROMYCIN
RIBOSIDES
RODENTS
SEPARATION PROCESSES
SYNTHESIS
VERTEBRATES