DISPOSITION OF THE CARBOXY-TERMINUS TAIL OF RABBIT LACTASE-PHLORHIZINHYDROLASE ELUCIDATED BY PHOSPHORYLATION WITH PROTEIN-KINASE-A IN-VITRO AND IN TISSUE-CULTURE
P. Keller et al., DISPOSITION OF THE CARBOXY-TERMINUS TAIL OF RABBIT LACTASE-PHLORHIZINHYDROLASE ELUCIDATED BY PHOSPHORYLATION WITH PROTEIN-KINASE-A IN-VITRO AND IN TISSUE-CULTURE, FEBS letters, 368(3), 1995, pp. 563-567
The intracellular disposition of the carboxy-terminus tail of rabbit l
actase-phlorizin hydrolase (LPH) is demonstrated, using a specific pho
sphorylation of Ser(1916) by protein kinase A (PKA). This phosphorylat
ion is shown to occur not only in vitro (with pare LPH and pure cataly
tic subunit of PKA), but also in an organ culture of the small intesti
ne, Cholera toxin, which is known to act in vivo on the membranes of t
he small intestine, with severe clinical consequences, and to elevate
the intracellular cyclic AMP of enterocytes, is shown to enhance signi
ficantly the phosphorylation ofLPH in intact cells grown as an organ c
ulture. These findings establish the cytosolic orientation of the carb
oxy-terminus tail of LPH in situ, and raise the possibility that the t
ail itself and its phosphorylation by PKA may have a physioiogical or
physiopathological significance.