Retinaldehyde-binding protein 1 (RLBP1, also called cellular retinaldehyde-binding protein, CRALBP) (Crabb et al. 1998) binds 11cROL (He et al. 2009) and is thought to enhance the activity of isomerase II and ARAT in experiments performed in cone-rich eyes from chickens (Mata et al. 2002, Mata et al. 2005).