Structural determinants and functional consequences of protein affinity for membrane rafts

Area of Science:

• Cell Biology
• Biophysics

Background:

• Eukaryotic plasma membranes feature functional lateral domains, including lipid-driven membrane rafts.
• Membrane rafts are crucial for plasma membrane functions, mediating protein recruitment and retention.

Purpose of the Study:

• To investigate the structural determinants of transmembrane protein partitioning into membrane raft domains.
• To develop a predictive model for raft affinity based on protein transmembrane domain (TMD) properties.

Main Methods:

• Direct quantification of raft affinity for numerous TMDs.
• Identification of physical features influencing TMD raft partitioning.
• Development of a mechanistic, physical model for predicting raft affinity from protein sequences.

Main Results:

• Three physical features—TMD surface area, length, and palmitoylation—independently affect raft partitioning.
• A predictive model was established, rationalizing experimental findings.
• Plasma membrane proteins exhibit higher raft affinity than intracellular membrane proteins.

Conclusions:

• Established general rules for TMD raft partitioning based on physical properties.
• The developed model accurately predicts raft affinity from protein sequences.
• Supports the central role of membrane rafts in protein sorting and membrane traffic.