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 STAT1 in adipocytes, or genes involved in innate immunity in macrophages and adipocytes (By similarity). Stress induces ATF7 phosphorylation that 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 (By similarity). 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 (By similarity). Acts as a dominant repressor of the E-selectin/NF-ELAM1/delta-A promoter. Acts as a negative regulator, inhibiting both ATF2 and ATF7 transcriptional activities. It may exert these effects by sequestrating in the cytoplasm the Thr-53 phosphorylating kinase, preventing activation. 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 (isoforms TAFII15 and TAFII20); the interaction potentiates the transactivation activity (isoform TAFII20 only) 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 (PubMed:29490055). Interacts with TERT (PubMed:29490055). (Microbial infection) Interacts with adenovirus 2 E1A; the interaction enhances the ATF7-mediated viral transactivation activity which requires the zinc-binding domains of both E1A and ATF7. Mainly nucleoplasmic. Restricted distribution to the perinuculear region. The sumoylated form locates to the nuclear periphery. Expressed in various tissues including heart, brain, placenta, lung and skeletal muscle. Highest levels in skeletal muscle. Lowest in lung and placenta. Strongly expressed in skeletal muscle. Also expressed at lower levels in heart and lung. 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. Sumoylation delays nuclear localization and inhibits transactivation activity through preventing binding to TAF12. RANBP2 appears to be the specific E3 ligase. 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 (PubMed:18950637). Social isolation stress as well as TNF-alpha also induce the phosphorylation of ATF7 (PubMed:29490055). Phosphorylated in proliferating colonic and small intestinal epithelial cells (By similarity). Belongs to the bZIP family.