Functional integrity of membrane protein rhodopsin solubilized by styrene-maleic acid copolymer

Stephanie G. Pitch, Weekie Yao, Istvan Szundi, Jonathan Fay, Eefei Chen, Anthony Shumate, David S. Kliger, David L. Farrens

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


Membrane proteins often require solubilization to study their structure or define the mechanisms underlying their function. In this study, the functional properties of the membrane protein rhodopsin in its native lipid environment were investigated after being solubilized with styrene-maleic acid (SMA) copolymer. The static absorption spectra of rhodopsin before and after the addition of SMA were recorded at room temperature to quantify the amount of membrane protein solubilized. The samples were then photobleached to analyze the functionality of rhodopsin upon solubilization. Samples with low or high SMA/rhodopsin ratios were compared to find a threshold in which the maximal amount of active rhodopsin was solubilized from membrane suspensions. Interestingly, whereas the highest SMA/rhodopsin ratios yielded the most solubilized rhodopsin, the rhodopsin produced under these conditions could not reach the active (Meta II) state upon photoactivation. The results confirm that SMA is a useful tool for membrane protein research, but SMA added in excess can interfere with the dynamics of protein activation.

Original languageEnglish (US)
Pages (from-to)3508-3515
Number of pages8
JournalBiophysical Journal
Issue number16
StatePublished - Aug 17 2021
Externally publishedYes

ASJC Scopus subject areas

  • Biophysics


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