Functional Cell Adhesion Receptors (Integrins) in Polymeric Architectures

Abstract

Integrins, as transmembrane heterodimeric receptors, have important functions in cell adhesion, migration, proliferation, survival apoptosis and signal transduction, in many physio- as well as pathophysiological settings. Characterisation of integrins and their ligand/antagonist binding is notoriously difficult, due to high integrin redundancy and ubiquity. Bypassing the intrinsic difficulties of cell-based integrin expression, purification and reconstitution, we present for the first time the synthesis of a heterodimeric integrin receptor and its assembly into a block-copolymeric membrane mimic. We present comprehensive data to demonstrate the synthesis of functionally active integrin αv β3, generated by in vitro membrane-assisted protein synthesis (iMAPS). This work represents the first step towards a robust and adaptable polymer-based platform for characterisation of integrin-ligand interactions.

Diblock copolymers enhance folding of a mechanosensitive membrane protein during cell-free expression

“…Likewise, recent advances in the creation of synthetic membrane mimetics have generated a variety of new amphiphiles (10, 11). Among these molecules, diblock copolymers have emerged as a new class of amphiphiles that expand the range of membrane properties beyond what is possible with biological lipids alone (12–15).…”

“…In addition, these vesicles provide opportunities as model membrane systems to investigate biological processes. While several membrane proteins have been incorporated into both pure polymeric and hybrid polymer/lipid membranes to date (8, 13–18), the effect of membrane composition on a wide range of protein behaviors remains largely unexplored. To effectively use biological membrane proteins in synthetic vesicles, we must understand how properties of vesicles and any nonnatural components they incorporate affect protein behavior from production to final activity.…”

Electrochemical Biosensors Based on S-Layer Proteins

“…Thus, the two before mentioned examples constitute proof-of-principle studies for the feasibility to utilize membrane-active peptides and membrane proteins reconstituted in SsLMs as electrochemical biosensor. The ability to reconstitute integral membrane proteins in defined structures like pure lipid bilayers [9,[132][133][134][135], block copolymer bilayers [136,137], and recently lipid bilayers blended with block copolymers [138,139] on electrode and sensor surfaces is one of the most important concerns in designing biomimetic sensing devices in future [9,10,[140][141][142].…”

Durable vesicles for reconstitution of membrane proteins in biotechnology

“… Integrin incorporation efficiency is not found to be dependent on the polymer block length. [ 44 ] Complex I PMOXA x -PDMS y -PMOXA x 8 polymers 9 ≤ x ≤ 65 23 ≤ y ≤ 165 Transmembrane electron transfer from NADH to an encapsulated quinone. Increasing membrane thickness increases the activity of complex I.…”

“…Removing detergent by diluting them to below the critical micelle concentration (CMC) and harvesting the polymersomes by centrifugation may not be possible as, unlike liposomes, many polymersomes are less dense than water and so cannot be spun down into a pellet. Direct incorporation of membrane proteins into polymersomes from cell-free synthesis has also been reported [ 44 ]. However, differences in properties between lipid and polymer systems mean that, for a given IMP, successful proteoliposome reconstitution protocols are not necessarily directly transferable to polymersome systems.…”