Transcription factor involved in unfolded protein response (UPR). Binds the DNA consensus sequence 5'-GTGXGCXGC-3' (PubMed:21767813). In the absence of endoplasmic reticulum (ER) stress, inserted into ER membranes, with N-terminal DNA-binding and transcription activation domains oriented toward the cytosolic face of the membrane. In response to ER stress, transported to the Golgi, where it is cleaved in a site-specific manner by resident proteases S1P/MBTPS1 and S2P/MBTPS2. The released N-terminal cytosolic domain is translocated to the nucleus to effect transcription of specific target genes. Plays a critical role in bone formation through the transcription of COL1A1, and possibly COL1A2, and the secretion of bone matrix proteins. Directly binds to the UPR element (UPRE)-like sequence in an osteoblast-specific COL1A1 promoter region and induces its transcription. Does not regulate COL1A1 in other tissues, such as skin (By similarity). Required to protect astrocytes from ER stress-induced cell death. In astrocytes, binds to the cAMP response element (CRE) of the BiP/HSPA5 promoter and participate in its transcriptional activation (By similarity). Required for TGFB1 to activate genes involved in the assembly of collagen extracellular matrix (PubMed:25310401). (Microbial infection) May play a role in limiting virus spread by inhibiting proliferation of virus-infected cells. Upon infection with diverse DNA and RNA viruses, inhibits cell-cycle progression by binding to promoters and activating transcription of genes encoding cell-cycle inhibitors, such as p21/CDKN1A (PubMed:21767813). Interacts with SMAD4, the interaction takes place upon TGFB1 induction and SMAD4 acts as CREB3L1 coactivator to induce the expression of genes involved in assembly of collagen extracellular matrix. ER membrane resident protein. Upon ER stress, translocated to the Golgi apparatus where it is cleaved. The cytosolic N-terminal fragment (processed cyclic AMP-responsive element-binding protein 3-like protein 1) is transported into the nucleus. Upon ER stress, transported into the nucleus. Expressed in several tissues, with highest levels in pancreas and prostate. Expressed at relatively lower levels in brain. Upon ER stress, translocated to the Golgi apparatus, where it is processed by regulated intramembrane proteolysis (RIP) to release the cytosol-facing N-terminal transcription factor domain. The cleavage is performed sequentially by site-1 and site-2 proteases (S1P/MBTPS1 and S2P/MBTPS2). RIP is induced by TGFB1 and ceramide (PubMed:25310401, PubMed:27499293). N-glycosylated. Ubiquitinated by HRD1/SYVN1; undergoes 'Lys-48'-linked ubiquitination, followed by rapid proteasomal degradation under normal conditions. Upon ER stress, SYVN1 E3 ubiquitin-protein ligase dissociates from its substrate, ubiquitination does not occur and CREB3L1 is stabilized. The disease may be caused by variants affecting the gene represented in this entry. OI16 affected patients show a genomic deletion encompassing CREB3L1 and the first exon of DGKZ. The absence of this exon does not affect all DGKZ isoforms, some are still produced at normal level. It cannot be ruled out that DGKZ could contribute to the phenotype, but in view of its role in bone formation, CREB3L1 is a strong OI16-causing candidate (PubMed:24079343). This hypothesis is corroborated by the observation of CREB3L1 knockout mice which exhibit features reminiscent of severe human osteogenesis imperfecta. Belongs to the bZIP family. ATF subfamily. Truncated N-terminus.