title: GABA from putrescine is bound in macromolecular form in keratinocytes.
abstract: We report for the first time that the neurotransmitter gamma-aminobutyric acid (GABA) exists in macromolecular form in keratinocytes. GABA derived from putrescine (Pu) has been identified as a component of acid-precipitable material of cultured human keratinocytes. Confluent, stratified cultures of human foreskin keratinocytes exposed to [3H]-Pu for 4 hours took up about 14% of the radioactivity from the medium and 1% of the total cell-associated radioactivity was precipitable by trichloroacetic acid (TCA). Both attached and shed cells were examined by HPLC for Pu and its radioactive metabolites in TCA-insoluble and TCA-soluble fractions. GABA accounted for the major portion (54%) of the radioactivity derived from Pu in the TCA-precipitable material of attached keratinocytes. Pu and spermidine represented lesser amounts, 35% and 9% respectively, of the total TCA-precipitable radioactivity. In addition, a large portion of acid soluble radioactivity derived from Pu (63%) was GABA, whereas Pu and spermidine represented 29% and 6% respectively of the total TCA-soluble radioactivity. The exact origin of GABA in acid-precipitable material, as well as its form of attachment, is currently under investigation.
mesh_terms: D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D006801:Humans; D006854:Hydrocortisone / Q000494:pharmacology; D007633:Keratins / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D011700:Putrescine / Q000378:metabolism*; D012867:Skin / Q000166:cytology / Q000378:metabolism*; D014316:Tritium; D005680:gamma-Aminobutyric Acid / Q000096:biosynthesis*
chemical_list: D014316:Tritium; D005680:gamma-Aminobutyric Acid; D007633:Keratins; D011700:Putrescine; D006854:Hydrocortisone