Related Experiment Video
Updated: Aug 9, 2026

Identifying Inhibitors of the HBx-DDB1 Interaction Using a Split Luciferase Assay System
Published on: December 21, 2019
Beta-sitosterol-3-O-beta-D-glucopyranoside: a eukaryotic DNA polymerase lambda inhibitor
Yoshiyuki Mizushina1, Rumi Nakanishi, Isoko Kuriyama
1Laboratory of Food & Nutritional Sciences, Department of Nutritional Science, Kobe-Gakuin University, Kobe, Hyogo 651-2180, Japan. mizushin@nutr.kobegakuin.ac.jp
Abstract:
Beta-sitosterol-3-O-beta-D-glucopyranoside (compound 1), a steroidal glycoside isolated from onion (Allium cepa L.) selectively inhibited the activity of mammalian DNA polymerase lambda (pol lambda) in vitro. The compound did not influence the activities of replicative DNA polymerases such as alpha, delta and epsilon, but also showed no effect even on the activity of pol beta which is thought to have a very similar three-dimensional structure to the pol beta-like region of pol lambda. Since parts of compound 1 such as beta-sitosterol (compound 2) and D-glucose (compound 3) did not influence the activities of any enzymes tested, the converted structure of compounds 2 and 3 might be important for pol lambda inhibition. The inhibitory effect of compound 1 on both intact pol lambda (i.e. residues 1-575) and a truncated pol lambda lacking the N-terminal BRCA1 C-terminus (BRCT) domain (133-575, del-1 pol lambda) was dose-dependent, and 50% inhibition was observed at a concentration of 9.1 and 5.4 microM, respectively. The compound 1-induced inhibition of del-1 pol lambda activity was non-competitive with respect to both the DNA template-primer and the dNTP substrate. On the basis of these results, the pol lambda inhibitory mechanism of compound 1 is discussed.
Related Concept Videos
Inhibitors of Bacterial DNA Synthesis
Eukaryotic Transcription Inhibitors
Eukaryotic transcription inhibitors usually contain two distinct domains, a DNA...
Drugs that Stabilize Microtubules
Inhibitors of Viral Protein Synthesis
Pharmacogenetics of Drug Targets: β₂-Adrenergic Receptors, Apo E, Thymidylate Synthase
Eukaryotic RNA Polymerases
All three eukaryotic RNAPs require specific transcription factors, of which the...