Fig. 8

Stimulated secretion depends on both vasopressin and glycopeptide. a AtT20 cells stably expressing wild-type provasopressin (wt) or the mutants without the glycopeptide (∆gp) or with the V5xA mutant hormone sequence (5xA) or both (5xA∆gp), or expressing the constitutive secretory protein A1Pi were grown and incubated for 30 min each with serum-free medium without (−) and then with BaCl₂ (+) to stimulate granule secretion for 30 min each. The media were collected, concentrated, and analyzed by SDS-gel electrophoresis and immunoblotting. To keep intensities within the diagnostic range of immunoblot analysis, a threefold larger aliquot (3x) of the control medium was analyzed than of the stimulation medium (1x). b Immunoblots as in A were quantified and stimulated secretion plotted as the ratio of stimulated to constitutive secretion (s/c). The mean and the individual values of four to five independent experiments are shown. Except for wild-type vs. V5xA, all pairwise comparisons are significantly different according to an unpaired two-tailed t test (the most important ones are indicated above the graph; *p < 0.05; **p < 0.01)