O. Shimada et al., DIFFERENCES IN THE DISTRIBUTION OF PROTEINS ASSOCIATED WITH OMEGA-CONOTOXIN RECEPTORS IN RAT PITUITARY-CELLS, Biomedical research, 14(4), 1993, pp. 265-272
Two monoclonal antibodies, SPM-1 and SPM-2, raised against brain synap
tic membrane specifically recognized two different omega-conotoxin rec
eptor-associated proteins with molecular masses of 36 kDa and 28 kDa,
respectively. In the anterior lobe of the rat pituitary, all secretory
cells were immunostained with SPM-2, but not with SPM-1, although fol
liculo-stellate cells were stained with both SPM-1 and SPM-2. Castrati
on or stimulation with hypothalamic hormones caused an increase in the
intensity of the SPM-2 staining in hormone-secretory cells. In the in
termediate lobe, all secretory cells showed a strong 28-kDa-protein im
munoreactivity. In the posterior lobe, the immunoreactivity to both SP
M-1 and SPM-2 was recognized in nerve endings. The results demonstrate
that hormone-secretory cells in the anterior and intermediate pituita
ry possess only 28-kDa protein, and thus two omega-conotoxin receptor-
associated proteins (36 kDa and 28 kDa) are not necessarily colocalize
d in these cells.