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Purification, Characterization, and Localization of 70 kDa Calcium-Sensitive Protein (Calelectrin) From Mammary Glands

Purification, Characterization, and Localization of 70 kDa Calcium-Sensitive Protein (Calelectrin) From Mammary Glands

J J Lozano, A H Haindl, V Rocha

J Cell Physiol. 1989 Nov;141(2):318-24.

PMID: 2530242

Abstract:

Mammary glands contain a group of calcium-sensitive proteins that bind to membranes in a calcium-dependent manner. Using the calcium-dependent binding to hydrophobic surfaces in combination with conventional techniques, we have purified the 70 kDa mammary calcium-binding protein (70 kDa M-CBP) to homogeneity. Antisera prepared to the 70 kDa M-CBP or to bovine liver 67 kDa calelectrin reacted in immunoblot analysis with the 70 kDa M-CBP antigen and with several additional mammary CBP species in crude tissue homogenates. Limited proteolysis of the 70 kDa M-CBP produced smaller immunoreactive species; extensive proteolysis resulted in more complete degradation of the protein. Identical data were obtained with digestion of 67 kDa calelectrin. The pl for the 70 kDa M-CBP was determined to be approximately 5.8; the same value reported for 67 kDa calelectrin. Phosphorylation of 70 kDa M-CBP was not detected in epithelial cell culture metabolic labeling. Immunohistochemical localization showed the protein to be located in ductal epithelia of virgin mouse mammary glands with a pattern of increased staining of the basal portions of the cells. Some stromal cells were also reactive. Apparently, the 70 kDa M-CBP and 67 kDa calelectrin are the same protein. Furthermore, like the 32.5 calelectrin (endonexin) and calpactin I/p36/lipocortin II, the 70 kDa protein appears to be a ductal epithelial cell associated protein in the mammary gland.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
AP342638544	m-CBP		342638-54-4	Price

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