Overview:

Signal transducers and activators of transcription (STAT)5A is phosphorylated by receptor associated protein kinases in response to cytokines and growth factors (1). STAT proteins are responsible for the differentiation of helper T cells, thus playing key roles in regulating immune functions. In BCR-ABL-positive cells, STAT5 is constitutively activated by tyrosine phosphorylation. STAT5 activation results in upregulation of Bcl-XL and results in increased resistance to apoptosis. STAT5 is involved in expression and growth hormone-mediated sexually dimorphic regulation of cytochrome P450 3A10/lithocholic acid 6 beta-hydroxylase (2). STAT5A is phosphorylated at Ser780 in response to IL-2 stimulation (3).

References:

1. Wang, D. et al: Naturally occurring dominant negative variants of Stat5. Molec. Cell Biol. 16: 6141-6148, 1996.

2. A Subramanian et al: STAT 5 and NF-Y are involved in expression and growth hormone-mediated sexually dimorphic regulation of cytochrome P450 3A10/lithocholic acid 6beta-hydroxylase. Nucleic Acids Res. 1998; 26(9): 2173–2178.

3. Xue H H. et al: Serine phosphorylation of Stat5 proteins in lymphocytes stimulated with IL-2. Int Immunol. 2002 Nov;14(11):1263-71.