+ Site Statistics
+ Search Articles
+ PDF Full Text Service
How our service works
Request PDF Full Text
+ Follow Us
Follow on Facebook
Follow on Twitter
Follow on LinkedIn
+ Subscribe to Site Feeds
Most Shared
PDF Full Text
+ Translate
+ Recently Requested

Alterations in in situ prolactin secretory granule morphology and immunoactivity by thiols and divalent cations



Alterations in in situ prolactin secretory granule morphology and immunoactivity by thiols and divalent cations



Endocrinology 126(1): 512-518



The mechanisms involved in PRL storage in secretory granules are generally poorly understood. Recent studies with isolated granules, however, have suggested that granule storage forms may be relatively osmotically inactive due to oligomerization involving hormonal intermolecular disulfide bonds. Thus, expenditure of metabolic energy by the cell in order to maintain granule integrity would be reduced. When secretion is stimulated, oligomer depolymerization by thiol exchange mechanisms has been proposed to occur before or even concomitant with exocytosis. The present studies were designed to investigate the influence of metabolic inhibitors, thiols, and divalent cations on PRL storage in situ, rather than in isolated granules. The results suggest that 1) PRL granules require little energy to maintain their structure, since a combination of azide (10 mM), fluoride (10 mM), and cyanide (1 mM) had no effect on PRL granule morphology in normal anterior pituitary cells in primary culture; 2) disulfide linkages are involved in the osmotic activity of the PRL granule contents, since thiols induced granule swelling in lightly fixed cells; and 3) thiols and divalent cations are capable of altering the arrangement of stored hormone molecules, since PRL immunoactivity could be modified by these agents in glycol methacrylate-embedded exposed granule cores.

Please choose payment method:






(PDF emailed within 0-6 h: $19.90)

Accession: 001750715

Download citation: RISBibTeXText

PMID: 2294001

DOI: 10.1210/endo-126-1-512


Related references

Divalent cations inhibit growth hormone and prolactin release from pituitary secretory granules. Clinical Research 30(4): 766A, 1982

Detectability of pituitary PRL and GH by immunoassay is increased by thiols and suppressed by divalent cations. Endocrinology 112(5): 1880-1882, 1983

Secretory granule growth hormone and prolactin release: independence from granule membrane ATPase. Endocrinology 114(3): 717-724, 1984

Activation of hepatic guanylate cyclase by N-methyl-N'-nitro-N-nitrosoguanidine. Effects of thiols, N-ethylmaleimide, and divalent cations. Journal of Biological Chemistry 252(16): 5804-5814, 1977

Intragranular prolactin phosphorylation and kallikrein cleavage are regulated by zinc and other divalent cations. Endocrine 4(3): 249-257, 1996

Effects of monovalent and divalent cations on Ca2+ fluxes across chromaffin secretory membrane vesicles. Journal of Neurochemistry 41(5): 1269-1276, 1983

A freeze-substitution method for localizing divalent cations: examples from secretory systems. Federation Proceedings 39(10): 2802-2808, 1980

Divalent cations increase lipid order in erythrocytes and susceptibility to secretory phospholipase A2. Biophysical Journal 86(4): 2251-2260, 2004

Alterations of mammalian oocyte meiosis I with divalent cations and calmodulin. Cell Calcium 3(2): 153-162, 1982

DNA denaturation in situ. Effect of divalent cations and alcohols. Journal of Cell Biology 68(1): 1-10, 1976

Depletion of divalent cations within the secretory pathway inhibits the terminal glycosylation of complex carbohydrates of thyroglobulin. Biochimie 81(5): 497-504, 1999

Calcitonin-like immunoreactivity in human milk, longitudinal alterations and divalent cations. Acta Physiologica Scandinavica 122(4): 461-464, 1984

Prolactin (PRL) is a zinc-binding protein. I. Zinc interactions with monomeric PRL and divalent cation protection of intragranular PRL cysteine thiols. Endocrinology 137(3): 809-816, 1996

Comparative effects of divalent cations on the methylmercury-induced alterations of acetylcholine release. Journal of Pharmacology and Experimental Therapeutics 240(2): 451-459, 1987

Proteolytic processing of prolactin prl occurs during secretory granule condensation. Journal of Cell Biology 103(5 PART 2): 188A, 1986