IDENTIFICATION OF 3 PROTEINS IN THE EYE OF APLYSIA, WHOSE SYNTHESIS IS ALTERED BY SEROTONIN (5-HT) - POSSIBLE INVOLVEMENT OF THESE PROTEINSIN THE OCULAR CIRCADIAN SYSTEM

Previous results using translation inhibitors in the ocular circadian system of Aplysia suggest that protein synthesis may be involved in th e light and serotonin (5-HT) entrainment pathways or perhaps in the ci rcadian oscillator. Proteins have been previously identified whose syn thesis was altered by treatments of light capable of perturbing the ph ase of the circadian rhythm in the eye of Aplysia. We extended these s tudies by investigating the effects of other treatments that perturb t he ocular circadian rhythm on protein synthesis. 5-HT altered the synt hesis of nine proteins. Interestingly, five of the proteins affected b y treatments with 5-HT were previously shown to be affected by treatme nts with light. Four of the proteins affected by treatments with 5-HT were also affected by treatments with analogs of cAMP, a treatment whi ch mimics the effects of 5-HT on the ocular circadian rhythm. To ident ify the cellular function of some of these proteins, we obtained their partial amino acid sequences, Based on these sequences and additional characterizations, a 78-kDa, pI 5.6 Aplysia protein appears to be glu cose-regulated protein 78/binding protein, and a 36-kDa, pI 5.7 Aplysi a protein appears to be porin/voltage-dependent anion channel. Heat sh ock experiments on Aplysia eyes revealed that yet another one of the A plysia proteins (70 kDa) affected by 5-HT appears to be a heat-inducib le member (heat shock protein 70) of the family of heat shock proteins . These findings suggest that these three identified proteins, togethe r or individually, maybe involved in some way in the regulation of the timing of the circadian oscillator in the eye of Aplysia.