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Titolo:
Membranes as possible pacemakers of metabolism
Autore:
Hulbert, AJ; Else, PL;
Indirizzi:
Univ Wollongong, Metab Res Ctr, Wollongong, NSW 2522, Australia Univ Wollongong Wollongong NSW Australia 2522 ongong, NSW 2522, Australia Univ Wollongong, Dept Biol Sci, Wollongong, NSW 2522, Australia Univ Wollongong Wollongong NSW Australia 2522 ongong, NSW 2522, Australia Univ Wollongong, Dept Biomed Sci, Wollongong, NSW 2522, Australia Univ Wollongong Wollongong NSW Australia 2522 ongong, NSW 2522, Australia
Titolo Testata:
JOURNAL OF THEORETICAL BIOLOGY
fascicolo: 3, volume: 199, anno: 1999,
pagine: 257 - 274
SICI:
0022-5193(19990807)199:3<257:MAPPOM>2.0.ZU;2-Y
Fonte:
ISI
Lingua:
ENG
Soggetto:
FATTY-ACID COMPOSITION; MAMMALIAN ENDOTHERMIC METABOLISM; HOMEOVISCOUS ADAPTATION; BIOLOGICAL-MEMBRANES; PROTON PERMEABILITY; INNER MEMBRANE; LIVER-MITOCHONDRIA; PLASMA-MEMBRANES; SODIUM-PUMP; PROTEIN FUNCTION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
98
Recensione:
Indirizzi per estratti:
Indirizzo: Hulbert, AJ Univ Wollongong, Metab Res Ctr, Wollongong, NSW 2522, Australia Univ Wollongong Wollongong NSW Australia 2522 2522, Australia
Citazione:
A.J. Hulbert e P.L. Else, "Membranes as possible pacemakers of metabolism", J THEOR BIO, 199(3), 1999, pp. 257-274

Abstract

Basal metabolic rate (BMR) varies dramatically among vertebrate species, both (i) being several fold higher in the endothermic mammals and birds compared to the ectothermic reptiles, amphibians and fish, and (ii) being much greater, on a body mass basis, in small vertebrates compared to large vertebrates. These differences in whole animal BMR are also manifest at the cellular level with substantial contributions to basal metabolic activity from the maintenance of various trans-membrane gradients. The percentage contribution of various processes to basal metabolism is remarkably consistent between different vertebrates and when BMR varies, the components of metabolicactivity vary in relative unison. Membrane composition also varies betweenvertebrates and the degree of polyunsaturation of membrane phospholipids is correlated with cellular metabolic activity. In general, the tissue phospholipids and thus membrane bilayers of endotherms are more polyunsaturated than those from similar-sized ectotherms. In mammals membrane polyunsaturation is allometrically related to body mass. We suggest that membranes can act as pacemakers for overall metabolic activity. We propose that such membrane polyunsaturation increases the molecular activity of many membrane-bound proteins and consequently some specific membrane leak-pump cycles and cellular metabolic activity. We hypothesize a possible mechanistic basis for this effect that is based on a greater transfer of energy during intermolecular collisions of membrane proteins with the unsaturated two carbon units (C = C) of polyunsaturates compared to the single carbon units of saturated acyl chains, as well as the more even distribution of such units throughoutthe depth of the bilayer when membranes contain polyunsaturated acyl chains compared to monounsaturated ones. The proposed pacemaker role of differences in membrane bilayer composition is briefly discussed with respect to the brain (and sensory cells), evolution of mammalian endothermic metabolism,and its clinical implications for humans. (C) 1999 Academic Press.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 10/07/20 alle ore 09:16:41