Lipids covalently bonded to pteridines and to nucleotides may bind neurotransmitters, and may be cleaved into second messengers for opiates.
By hypothesis: 1.) lipid-pteridines and lipid-nucleotides, while fixed in the external side of membranes at the ends of nerve cells, bind neurotransmitters and perhaps opiates; 2.) during their normal metabolism in animals they are cleaved by phospholipases into pteridines and nucleotides which act as 2nd messengers for opiates. These 2nd messengers, some with tri-iodo-thyronine, act by sandwiching about circulating neurotransmitters; 3.) dinucleotides containing neopterin are specific 2nd messengers for steroids; and 4.) lipid-RNAs are the molecular locations in the brain which contain memories.
D001921:Brain / Q000378:metabolism*; D004723:Endorphins / Q000378:metabolism*; D006801:Humans; D050356:Lipid Metabolism; D008954:Models, Biological; D018377:Neurotransmitter Agents / Q000378:metabolism*; D009711:Nucleotides / Q000378:metabolism*; D011621:Pteridines / Q000378:metabolism*; D009435:Synaptic Transmission; D014284:Triiodothyronine / Q000378:metabolism
D004723:Endorphins; D018377:Neurotransmitter Agents; D009711:Nucleotides; D011621:Pteridines; D014284:Triiodothyronine