Endoplasmic reticulum (ER)-bound sequence-specific transcription factor that directly binds DNA and activates transcription (PubMed:10984507, PubMed:15845366, PubMed:16940180, PubMed:19779205, PubMed:9271389). Plays a role in the unfolded protein response (UPR), promoting cell survival versus ER stress-induced apoptotic cell death (PubMed:15845366, PubMed:16940180). Also involved in cell proliferation, migration and differentiation, tumor suppression and inflammatory gene expression. Acts as a positive regulator of LKN- 1/CCL15-induced chemotaxis signaling of leukocyte cell migration (PubMed:15001559, PubMed:17296613, PubMed:19779205). Associates with chromatin to the HERPUD1 promoter (PubMed:16940180). Also induces transcriptional activation of chemokine receptors (PubMed:17296613, PubMed:18587271). {ECO:0000269|PubMed:10984507, ECO:0000269|PubMed:15001559, ECO:0000269|PubMed:15845366, ECO:0000269|PubMed:16940180, ECO:0000269|PubMed:17296613, ECO:0000269|PubMed:18587271, ECO:0000269|PubMed:19779205, ECO:0000269|PubMed:9271389}. (Microbial infection) Plays a role in human immunodeficiency virus type 1 (HIV-1) virus protein expression. . [Isoform 1]: (Microbial infection) May play a role as a cellular tumor suppressor that is targeted by the hepatitis C virus (HCV) core protein. . [Isoform 1]: (Microbial infection) Plays a role in herpes simplex virus-1 (HSV-1) latent infection and reactivation from latency. Represses the VP16-mediated transactivation of immediate early genes of the HSV-1 virus by sequestering host cell factor-1 HCFC1 in the ER membrane of sensory neurons, thereby preventing the initiation of the replicative cascade leading to latent infection. . [Isoform 2]: Functions as a negative transcriptional regulator in ligand-induced transcriptional activation of the glucocorticoid receptor NR3C1 by recruiting and activating histone deacetylases (HDAC1, HDAC2 and HDAC6). Also decreases the acetylation level of histone H4. Does not promote the chemotactic activity of leukocyte cells. . [Processed cyclic AMP-responsive element-binding protein 3]: This is the transcriptionally active form that translocates to the nucleus and activates unfolded protein response (UPR) target genes during endoplasmic reticulum (ER) stress response. Binds the cAMP response element (CRE) (consensus: 5'-GTGACGT[AG][AG]-3') and C/EBP sequences present in many promoters to activate transcription of the genes. Binds to the unfolded protein response element (UPRE) consensus sequences sites. Binds DNA to the 5'-CCAC[GA]-3'half of ERSE II (5'- ATTGG-N-CCACG-3'). . [Processed cyclic AMP-responsive element-binding protein 3]: (Microbial infection) Activates transcription of genes required for reactivation of the latent HSV-1 virus. Its transcriptional activity is inhibited by CREBZF in a HCFC1-dependent manner, by the viral transactivator protein VP16. Binds DNA to the cAMP response element (CRE) (consensus: 5'-GTGACGT[AG][AG]-3') and C/EBP sequences present in many viral promoters. . [Processed cyclic AMP-responsive element-binding protein 3]: (Microbial infection) Its transcriptional activity is inhibited by CREBZF in a HCFC1-dependent manner, by the viral transactivator HCV core protein. . This is the function of Ensembl gene identifier ENSG00000107175 (CREB3, cAMP responsive element binding protein 3).