PHA-P, a lectin from Phaseolus vulgaris-P (red kidney bean), is the protein form of phytohemagglutinin (PHA). It consists of two closely related proteins, PHA-E and PHA-L, which agglutinate erythrocytes and lymphocytes, respectively. PHA is well-known as a selective T cell mitogen [1].
In addition to these activities, PHA is known to greatly enhance HIV-1 replication by mimicking T cell activation [2, 3]. Specifically, PHA binds to sugars on glycosylated surface proteins, including T cell receptor (TCR), and thereby crosslinks them.
This triggers calcium-dependent signaling pathways leading to NFAT (nuclear factor of activated T cells) activation.
References:
- Movafagh A. et al., 2011. The significance application of indigenous Phytohemagglutinin (PHA) mitogen on metaphase and cell culture procedure. Iran J Pharm Res. 10(4):895-903.
- Kinoshita S., 1997. The T cell activation factor NF-ATc positively regulates HIV-1 replication and gene expression in T cells. 46(2): 237–249. Immunity. 6(3):235-44.
- Fortin JF. et al., 2001. Regulation of nuclear factor of activated T cells by phosphotyrosyl-specific phosphatase activity: a positive effect on HIV-1 long terminal repeat-driven transcription and a possible implication of SHP-1. Blood. 97(8):2390-400.
