Specific localization of tissue-type transglutaminase in adrenocorticotropin-producing cells of the human pituitary gland as demonstrated by immunohistochemistry.
The distribution of transglutaminases, the Ca2+-dependent protein cross-linking enzymes, in the human pituitary gland was investigated by immunohistological methods using specific antibodies. Tissue-type transglutaminase was specifically localized in ACTH-producing cells, and the cells producing GH, PRL, TSH, FSH, and LH contained no appreciable amount of the enzyme. No detectable plasma-type transglutaminase (coagulation factor XIII) was found in pituitary tissue. In a previous study we demonstrated that ACTH-producing cells contain very little Ca2+-dependent proteinases (calpain), but a remarkable amount of their inhibitor, calpastatin. Pituitary gland cells producing hormones other than ACTH contained calpains, but no detectable calpastatin. These results collectively suggest that intracellular substrate proteins in ACTH-producing cells are protected from Ca2+-dependent degradation and are substrates for Ca2+-dependent cross-linking catalyzed by the tissue-type transglutaminase. In other pituitary gland cells, conversely, the intracellular substrate proteins are more likely to undergo Ca2+-dependent degradation than cross-linking.
D000293:Adolescent; D000324:Adrenocorticotropic Hormone / Q000096:biosynthesis*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000906:Antibodies / Q000276:immunology; D000918:Antibody Specificity; D000941:Antigens / Q000276:immunology; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007223:Infant; D008297:Male; D008875:Middle Aged; D010902:Pituitary Gland / Q000166:cytology / Q000201:enzymology* / Q000378:metabolism; D013194:Staining and Labeling; D011503:Transglutaminases / Q000276:immunology / Q000378:metabolism*
D000906:Antibodies; D000941:Antigens; D000324:Adrenocorticotropic Hormone; D011503:Transglutaminases