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(cell and molecular biology)
A fragment of the endoplasmic reticulum.
A minute granule of protoplasm.



a fragment in the endoplasmic network (bubbles about 1,000 angstroms diameter), formed when cells are destroyed during the homogenization of animal and plant tissues. The microsome fraction of the homogenate is isolated by differential centrifugation. There are two types of microsomes: smooth-surfaced and rough-surfaced (as a result of the distribution of ribosomes on the latter). Before the technique of separating cellular homogenates was perfected, the microsome fraction also included mitochondria.

References in periodicals archive ?
In case of pesticides, comparative in vitro metabolism studies using microsomes or intact cell systems of relevant experimental animals and human materials are a regulatory data requirement (EC, 2013) to determine the relevance of the toxicological animal data and to guide in the interpretation of findings and in further definition of the testing strategy.
Microsomes were prepared from pooled lung or OM tissues of male, 2-month-old Cyp2abfgs-null, CYP2A13-humanized, or CYP2A13/2F1-humanized mice.
Cytochrome p450-mediated metabolism of the HIV-1 protease inhibitor ritonavir (ABT-538) in human liver microsomes.
Effect of purified saponin mixture from Astragalus corniculatus on enzyme- and non-enzyme-induced lipid peroxidation in liver microsomes from spontaneously hypertensive rats and normotensive rats.
Pooled human liver microsomes (HLMs) were purchased from XenoTech (Kansas, USA).
In 1962, Sato and Omura examined the carbon monoxide-combined pigment of liver microsomes which was originally reported by Klingenberg.
It is reported that liver microsomes induced cytochromes P450 to metabolize DEET to R0N1 (CYP2A6, 2C19, 3A4, and 3A5) and R1N0 (CYP1A2, 2B6, 2D6*1, and 2E1) (Usmani et al.
Microsomes and patients were genotyped for CYP3A5 rs776746 A>G (CYP3A5*3), CYP3A4 rs35599367 C>T (CYP3A4*22), POR rs1057868 C>T (POR*28), and PPARA rs4253728 G>A by use of Taqman[R] allelic discrimination assays on an ABI PRISM 7000 sequence detection system (Applied Biosystems).
In vitro metabolism of midazolam, triazolam, nifedipine, and testosterone by human liver microsomes and recombinant cytochromes p450: role of cyp3a4 and cyp3a5.
PA(s) were found to acetylate certain proteins mediated by an enzyme localized in rat liver microsomes.
12,13) An in vitro study reported that in humans the oxymorphone, formed by O-demethylation of oxycodone by the enzyme CYP2D6, accounts for 13% of oxycodone oxidative metabolism in liver microsomes.