Transduction pathways of GH in ovine mammary acini involving regulated and functional growth hormone receptors.

We have investigated the localization and regulation of growth hormone (GH) receptor-related proteins in the ovine mammary gland. Using a new rabbit polyclonal antibody (7122A) directed against the recombinant extracellular domain of GH receptor (GHR-ECD) for western blot assays, we found two bands with apparent molecular weights of 70,000 and 50-60,000 Da in ovine mammary gland solubilized proteins. The 70,000-protein was consistent with a membrane GH receptor form deprived of post-translational modifications such as phosphorylation, glycosylation or ubiquitin binding.

Developmental expression of pIgR gene in sheep mammary gland and hormonal regulation.

Secretory IgA found in external secretions are constituted by polymeric IgA (pIgA) bound to the extra-cellular part of the polymeric immunoglobulin receptor (pIgR). The receptor mediates transcytosis of pIgA across epithelial cells. The aim of the present study was to analyse the evolution of pIgR expression in the sheep mammary gland during the development of the mammary gland and to analyse its hormonal regulation.