Lipids covalently bonded to pteridines and to nucleotides may bind neurotransmitters, and may be cleaved into second...

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.