After bacteriorhodopsin, halorhodopsin may be the best type I (microbial) opsin studied. Peak absorbance of the halorhodopsin retinal complex is about 570 nm.
Similar to bacteriorhodopsin, halorhodopsin might be among the most researched type I (microbial) opsins. The peak absorption of the halorhodopsin retinal complex is around 570 nm.