Stress-responsive chromatin regulator that plays a role in various biological processes including innate immunological memory, adipocyte differentiation or telomerase regulation (PubMed:29490055). In absence of stress, contributes to the formation of heterochromatin and heterochromatin-like structure by recruiting histone H3K9 tri- and di-methyltransferases thus silencing the transcription of target genes such as Htr5b, STAT1 in adipocytes, or genes involved in innate immunity in macrophages and adipocytes (PubMed:19893493, PubMed:31294895, PubMed:30826729). Phosphorylation of ATF7 disrupts interactions with histone methyltransferase and enhances the association with coactivators containing histone acetyltransferase and/or histone demethylase, leading to disruption of the heterochromatin-like structure and subsequently transcriptional activation (PubMed:19893493). In response to TNF-alpha, which is induced by various stresses, phosphorylated ATF7 and telomerase are released from telomeres leading to telomere shortening (PubMed:29490055). Also plays a role in maintaining epithelial regenerative capacity and protecting against cell death during intestinal epithelial damage and repair (PubMed:31958521). Homodimer; binds DNA as homodimer. Heterodimer; heterodimerizes with other members of ATF family and with JUN family members. Interacts with JNK2; the interaction does not phosphorylate ATF7 but acts as a docking site for other ATF-associated partners such as JUN family members. Interacts (via its transactivation domain) with TAF12 the interaction potentiates the transactivation activity and is inhibited by ATF7 sumoylation. Interacts with TAF4; the interaction inhibits the TAF12-dependent transactivation. Interacts with MAPK9; the interaction does not phosphorylate ATF7 but acts as a docking site for ATF7-associated partners such as JUN. Interacts with Ku complex components XRCC6 and XRCC7. Interacts with TERT. Mainly nucleoplasmic. Restricted distribution to the perinuculear region. The sumoylated form locates to the nuclear peiphery. On EGF stimulation, phosphorylated first on Thr-53 allowing subsequent phosphorylation on Thr-51. This latter phosphorylation prevents sumoylation, increases binding to TAF12 and enhances transcriptional activity (By similarity). Social isolation stress as well as TNF-alpha also induce the phosphorylation of ATF7 (PubMed:19893493, PubMed:29490055). Phosphorylated in proliferating colonic and small intestinal epithelial cells (PubMed:31958521). Sumoylation delays nuclear localization and inhibits transactivation activity through preventing binding to TAF12. RANBP2 appears to be the specific E3 ligase. Mice exhibit abnormal behaviors and increased 5-HT receptor 5B (Htr5b) mRNA levels in the dorsal raphe nuclei (PubMed:19893493). They also exhibit reduced adipose tissue mass, showing a role for ATF7 in adipocyte differentiation (PubMed:30826729). They develop severe ulceration and inflammation associated with increased epithelial apoptosis on dextran-sulfate sodium (DSS) exposure and were less able to regenerate colonic crypts on irradiation (PubMed:31294895). When combined with loss of ATF2, mice show even more epithelial damage in response to DSS (PubMed:31958521). In addition, loss of ATF7 leads to telomere shortening and chromosome instability (PubMed:29490055). Belongs to the bZIP family.