ISSN:
1432-0878
Keywords:
Melanotrophs
;
Immunogold technique
;
Secretory vesicles
;
γ3-MSH
;
α-MSH
;
Endorphins
;
Rabbit
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary The immunogold technique, employing antisera with clear-cut specificities, was used to localise different processing stages of pro-opiomelanocortin (POMC) in rabbit melanotropic cells. While the antiserum against γ 3-MSH labelled all the secretory granules including intrasaccular condensations in the Golgi apparatus, antisera against α-MSH only labelled extra-Golgi secretory vesicles (SV). All extra-Golgi SV were likewise labelled with the three antisera against α-MSH used, despite their different specificities for the desacetylated, N-acetylated or C-amidated forms of the peptide. The antibody against β-endorphin also labelled the extra-Golgi SV, while only some SV were labelled with the antibody against γ-endorphin. These results correlate with biochemical data in favour of mainly — if not exclusively — intragranular processing of POMC. Except for γ3-MSH, the cleavage of which could coincide with Golgi packaging of secretory material, other post-translational modifications of the precursor seem to occur when SV are discharged outside the Golgi area. The cleavage of γ-endorphin appears to be a later step in POMC processing, occurring in some mature SV.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00214549
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