Related Experiment Video
Updated: Feb 7, 2026

Synthesis of Protein Bioconjugates via Cysteine-maleimide Chemistry
Published on: July 20, 2016
Cysteine-mediated decyanation of vitamin B12 by the predicted membrane transporter BtuM
S Rempel1, E Colucci1, J W de Gier2
1Groningen Biomolecular and Biotechnology Institute (GBB), University of Groningen, Nijenborgh 4, 9474 AG, Groningen, The Netherlands.
Abstract:
Uptake of vitamin B12 is essential for many prokaryotes, but in most cases the membrane proteins involved are yet to be identified. We present the biochemical characterization and high-resolution crystal structure of BtuM, a predicted bacterial vitamin B12 uptake system. BtuM binds vitamin B12 in its base-off conformation, with a cysteine residue as axial ligand of the corrin cobalt ion. Spectroscopic analysis indicates that the unusual thiolate coordination allows for decyanation of vitamin B12. Chemical modification of the substrate is a property other characterized vitamin B12-transport proteins do not exhibit.
More Related Videos
08:18Author Spotlight: Unraveling Vitamin A Transport Mechanisms — Linking Liver Receptors to Vision Health Through RBPR2 and RBP4 Interactions
Published on: October 4, 2024
13:16Characterization of Membrane Transporters by Heterologous Expression in E. coli and Production of Membrane Vesicles
Published on: December 31, 2019
Related Concept Videos
Drug Absorption Mechanism: Carrier-Mediated Membrane Transport
Facilitated diffusion is a passive process that utilizes human Solute Carrier (SLC) transporters. These transporters bind to the drug, undergo structural...
Membrane Transporters
Transporters are mainly composed of alpha-helices, built from bundles of ten or more helices traversing the plasma membrane. The solute-binding sites are located midway, where some of the helices are broken or distorted, making space for the binding site through...
Carrier-Mediated Transport
Active transport involves two types of membrane-spanning transporters: uptake and efflux. Uptake transporters are expressed in the small...
The Significance of Membrane Transport
Transporters facilitate either an active or passive movement of solutes. They can allow a single-molecule transport down its...
Cellular Membranes and Drug Transport
Phospholipids arrange themselves into a bilayer, with hydrophilic heads oriented outward and hydrophobic tails facing inward.
Membrane Asymmetry Regulating Transporters
Flippase
Eukaryotic flippases are type-IV P-type ATPases or P4-ATPases belonging to P-type ATPase family proteins that are membrane-bound pumps involved in the ATP-mediated transport of ions and molecules across the membrane. Flippases flip specific phospholipids from the outer to the inner leaflet of a membrane. All P4-ATPases have one...