Could be involved in regulation of growth and intracellular survival. Residues 76-280 interact with EsxB and an artificial EsxB-EsxA heterodimer (PubMed:19854905). Induced during stationary phase. Phosphorylated at Ser-70. Inactivation does not abolish EsxA (ESAT-6) secretion, EsxA-specific immunogenicity and enhanced virulence (PubMed:16368961). Deletion mutants multiply more efficiently compared to wild-type strains (PubMed:26228622). Elicits a prominent immune response in human tuberculosis patients. Contains several epitopes, particularly in the C-terminal region.