Faculty, Staff and Student Publications
Language
English
Publication Date
1-1-2024
Journal
Methods in Molecular Biology
DOI
10.1007/978-1-0716-3445-5_9
PMID
37930526
PMCID
PMC10755806
PubMedCentral® Posted Date
1-1-2025
PubMedCentral® Full Text Version
Author MSS
Abstract
A described simple and advanced protocol for Substituted Cysteine Accessibility Method as applied to transmembrane (TM) orientation (SCAM™) permits a topology analysis of proteins in their native state and can be universally adapted to any membrane system to either systematically map an uniform or identify and quantify the degree of mixed topology or establish transmembrane assembly dynamics from relatively static experimental data such as endpoint topologies of membrane proteins. In this approach, noncritical individual amino acids that are thought to reside in the putative extracellular or intracellular loops of a membrane protein are replaced one at the time by cysteine residue, and the orientation with respect to the membrane is evaluated by using a pair of membrane-impermeable non-detectable and detectable thiol-reactive labeling reagents. For the most water-exposed cysteine residues in proteins, the thiol pKa lies in the range of 8-9, and formation of cysteinyl thiolate ions is optimum in aqueous rather in a nonpolar environment. These features and the ease of specific chemical modification with thiol reagents are central to SCAM™. Membrane side-specific sulfhydryl labeling allows to discriminate "exposed, protected or dynamic" cysteines strategically "implanted" at desired positions throughout cysteine less target protein template. The strategy described is widely used to map the topology of membrane protein and establish its transmembrane dynamics in intact cells of both diderm (two-membraned) Gram-negative and monoderm (one-membraned) Gram-positive bacteria, cell-derived oriented membrane vesicles, and proteoliposomes.
Keywords
Membrane Proteins, Cysteine, Amino Acids, Sulfhydryl Compounds, Sulfhydryl Reagents, Membrane protein, Topology, Cysteine, Maleimides, SCAM™
Published Open-Access
yes
Recommended Citation
Mikhail Bogdanov, "Exploring Uniform, Dual, and Dynamic Topologies of Membrane Proteins by Substituted Cysteine Accessibility Method (SCAM™)" (2024). Faculty, Staff and Student Publications. 2855.
https://digitalcommons.library.tmc.edu/uthmed_docs/2855