# SPR spectroscopic analysis of myosin binding to wild type and mutant UNC45B

## TL;DR

This study uses SPR spectroscopy to show that a specific mutation in UNC45B significantly reduces its ability to bind myosin.

## Contribution

The novel contribution is the direct quantification of myosin binding affinities to wild type and mutant UNC45B using SPR.

## Key findings

- Deleting the client-binding loop in UNC45B causes a dramatic decrease in myosin binding affinity.
- SPR spectroscopy was used to directly measure binding affinities between myosin and UNC45B variants.
- The UCS domain is confirmed as critical for UNC45B's chaperoning function.

## Abstract

UNC45B is a multidomain molecular chaperone that is essential for the proper folding and function of myosin. It has previously been demonstrated that the UCS domain is responsible for the chaperoning function of UNC45B and that removing its client-binding loop leads to a significant change in its solution conformation and a reduced chaperoning function. Here, we report the direct quantification of affinities of myosin binding to wild type and mutant UNC45B using surface plasmon resonance (SPR) spectroscopy. We found that deletion of the client-binding loop in UNC45B resulted in a dramatic decrease in myosin affinity.