Heterogeneous distribution of kinesin–streptavidin complexes revealed by mass photometry

Kinesin–streptavidin complexes are widely used in microtubulebased active-matter studies. The stoichiometry of the complexes is empirically tuned but experimentally challenging to determine. Here, mass photometry measurements reveal heterogenous distributions of kinesin–streptavidin complexes. Our binding model indicates that heterogeneity arises from both the kinesin–streptavidin mixing ratio and the kinesin-biotinylation efficiency.