The carriage of a solute across a biological membrane
from low to high concentration which requires the expenditure of (metabolic) energy.
PAC, 1992, 64, 143
(Glossary for chemists of terms used in biotechnology (IUPAC Recommendations 1992))
on page 145
IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by
A. D. McNaught and A.Wilkinson. Blackwell Scientific Publications, Oxford (1997).
XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic,
J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8. https://doi.org/10.1351/goldbook