Fluorescent conjuates of α -Bungarotoxin bind to the nicotinic acetylcholine receptor with high affinity, and thus can be used to image the distribution of the receptor at the neuromuscular junctions. Deep-red fluorescent sulforhodamine-101 (also known at Texas® Red alpha; -bungarotoxin has excitation/emission at 593/613 nm. Texas Red is a registered trademark of Thermo Fisher Scientific.