BAG3 ELISA Kits

Bag1 is a regulator of heat shock protein 70 kDa (Hsp70/Hsc70) family proteins that interacts with steroid hormone receptors. Four isoforms of Bag1 have been recognized: Bag1, Bag1S, Bag1M (RAP46/HAP46), and Bag1L. Although Bag1L, Bag1M, and Bag1 can bind the androgen receptor (AR) in vitro, only Bag1L enhanced AR transcriptional activity. Because Bag1L is the only isoform that is constitutively present in the nucleus, one possible explanation is that the higher nuclear levels of Bag1L may be responsible for its physical and functional interactions with AR complexes. Forced nuclear targeting of Bag1M, but not Bag1 or Bag1S, resulted in potent AR coactivation, indicating that Bag1M possesses the necessary structural features provided it is expressed within the nucleus. Previous studies have shown that Bag1L does not alter the ligand-dependent nuclear translocation of the AR. Also, Bag1 proteins have been reported to interact with and regulate the activity of several members of the nuclear receptor superfamily. For example, Bag1M and Bag1L have been found to repress the activity of the glucocorticoid receptor and Bag1 represses the transcriptional activity of retinoic acid receptors.

The co-chaperone protein Bcl-2-associated athanogene-1 (BAG-1) is overexpressed in breast cancer and has been incorporated in the oncotype DX and PAM50 breast cancer prognostic assays. Bcl-2-associated athanogene-1 exists as multiple protein isoforms that interact with diverse partners, including chaperones Hsc70/Hsp70, Ser/Thr kinase Raf-1 and Bcl-2, to promote cancer cell survival. The BAG-1L isoform specifically binds to and increases the transcriptional activity of oestrogen receptor in cells, and in some, but not all studies, BAG-1 expression is predictive of clinical outcome in breast cancer.