A possible taste receptor for fat, CD36 , has been identified.  CD36 has been localized to the circumvallate and foliate papillae , which are present in taste buds ,  and research has shown that the CD36 receptor binds long chain fatty acids .  Differences in the amount of CD36 expression in human subjects was associated with their ability to taste fats,  creating a case for the receptor's relationship to fat tasting. Further research into the CD36 receptor could be useful in determining the existence of a true fat-tasting receptor.
Intracellular receptors are receptors located inside the cell rather than on its cell membrane . Classic hormones that use intracellular receptors include thyroid and steroid hormones. Examples are the class of nuclear receptors located in the cell nucleus and cytoplasm and the IP 3 receptor located on the endoplasmic reticulum . The ligands that bind to them are usually intracellular second messengers like inositol trisphosphate (IP 3 ) and extracellular lipophilic hormones like steroid hormones . Some intracrine peptide hormones also have intracellular receptors.