The swordtail (Xiphophorus helleri) eye contains the A4 and B4 isozymes of lactate dehydrogenase (LDH) as do all vertebrates and in addition contains a distinctive lactate dehydrogenase, the E4 isozyme, found only in fish. LDH in the fish eye is located predominantly in the neural retina, especially in the inner segments of the photoreceptor cells. This neural retinal LDH activity consists mainly of the B4 and E4 isozymes which are more resistant than the A4 isozyme to inhibition by 1.8 M urea. The sclera, cornea, and lens possess mainly the urea‐sensitive A4 isozyme. The specific cellular location of the E4 isozyme suggests that it plays a role in the biochemistry of vision.
ASJC Scopus subject areas
- Animal Science and Zoology