Point mutation in codon 23

The first point mutation demonstrated in the
rhodopsin gene (Dryja et al., 1990) was a transversion
from cytosine to adenine in codon
23. This changed the codon CCC for proline (Pro)
into CAC for histidine (His). Since the proline in
position 23 occurs in more than ten related G
protein receptors, it must be very important for
normal function.