Protein kinase C, commonly abbreviated to PKC (EC 2.7.11.13), is a family of protein kinase enzymes that are involved in controlling the function of other proteins through the phosphorylation of hydroxyl groups of serine and threonine amino acid residues on these proteins, or a member of this family. PKC enzymes in turn are activated by signals such as increases in the concentration of diacylglycerol (DAG) or calcium ions (Ca2+). Hence PKC enzymes play important roles in several signal transduction cascades.
c-Jun N-terminal kinases (JNKs), were originally identified as kinases that bind and phosphorylate c-Jun on Ser-63 and Ser-73 within its transcriptional activation domain. They belong to the mitogen-activated protein kinase family, and are responsive to stress stimuli, such as cytokines, ultraviolet irradiation, heat shock, and osmotic shock. They also play a role in T cell differentiation and the cellular apoptosis pathway. Activation occurs through a dual phosphorylation of threonine (Thr) and tyrosine (Tyr) residues within a Thr-Pro-Tyr motif located in kinase subdomain VIII. Activation is carried out by two MAP kinase kinases, MKK4 and MKK7, and JNK can be inactivated by Ser/Thr and Tyr protein phosphatases. It has been suggested that this signaling pathway contributes to inflammatory responses in mammals and insects.
c-Jun is a protein that in humans is encoded by the JUN gene. c-Jun, in combination with c-Fos, forms the AP-1 early response transcription factor. It was first identified as the Fos-binding protein p39 and only later rediscovered as the product of the JUN gene. c-jun was the first oncogenic transcription factor discovered. The proto-oncogene c-Jun is the cellular homolog of the viral oncoprotein v-jun. The viral homolog v-jun was discovered in avian sarcoma virus 17 and was named for ju-nana, the Japanese word for 17. The human JUN encodes a protein that is highly similar to the viral protein, which interacts directly with specific target DNA sequences to regulate gene expression. This gene is intronless and is mapped to 1p32-p31, a chromosomal region involved in both translocations and deletions in human malignancies.
Activator protein 1 (AP-1) is a transcription factor that regulates gene expression in response to a variety of stimuli, including cytokines, growth factors, stress, and bacterial and viral infections. AP-1 controls a number of cellular processes including differentiation, proliferation, and apoptosis. The structure of AP-1 is a heterodimer composed of proteins belonging to the c-Fos, c-Jun, ATF and JDP families.
Mitogen-activated protein kinase 8 is a ubiquitous enzyme that in humans is encoded by the MAPK8 gene.
Protein kinase C epsilon type (PKCε) is an enzyme that in humans is encoded by the PRKCE gene. PKCε is an isoform of the large PKC family of protein kinases that play many roles in different tissues. In cardiac muscle cells, PKCε regulates muscle contraction through its actions at sarcomeric proteins, and PKCε modulates cardiac cell metabolism through its actions at mitochondria. PKCε is clinically significant in that it is a central player in cardioprotection against ischemic injury and in the development of cardiac hypertrophy.
Dual specificity mitogen-activated protein kinase kinase 2 is an enzyme that in humans is encoded by the MAP2K2 gene. It is more commonly known as MEK2, but has many alternative names including CFC4, MKK2, MAPKK2 and PRKMK2.
Serine/threonine-protein kinase PAK 2 is an enzyme that in humans is encoded by the PAK2 gene.
Dual specificity mitogen-activated protein kinase kinase 6 also known as MAP kinase kinase 6 or MAPK/ERK kinase 6 is an enzyme that in humans is encoded by the MAP2K6 gene, on chromosome 17.
Dual specificity mitogen-activated protein kinase kinase 3 is an enzyme that in humans is encoded by the MAP2K3 gene.
Protein kinase C theta (PKC-θ) is an enzyme that in humans is encoded by the PRKCQ gene. PKC-θ, a member of serine/threonine kinases, is mainly expressed in hematopoietic cells with high levels in platelets and T lymphocytes, where plays a role in signal transduction. Different subpopulations of T cells vary in their requirements of PKC-θ, therefore PKC-θ is considered as a potential target for inhibitors in the context of immunotherapy.
DNA damage-inducible transcript 3, also known as C/EBP homologous protein (CHOP), is a pro-apoptotic transcription factor that is encoded by the DDIT3 gene. It is a member of the CCAAT/enhancer-binding protein (C/EBP) family of DNA-binding transcription factors. The protein functions as a dominant-negative inhibitor by forming heterodimers with other C/EBP members, preventing their DNA binding activity. The protein is implicated in adipogenesis and erythropoiesis, and has an important role in the cell's stress response.
Protein kinase C eta type is an enzyme that in humans is encoded by the PRKCH gene.
5'-AMP-activated protein kinase subunit beta-1 is an enzyme that in humans is encoded by the PRKAB1 gene.
Pyruvate dehydrogenase lipoamide kinase isozyme 4, mitochondrial is an enzyme that in humans is encoded by the PDK4 gene. It codes for an isozyme of pyruvate dehydrogenase kinase.
Phosphatidylinositol-4-phosphate 3-kinase C2 domain-containing beta polypeptide is an enzyme that in humans is encoded by the PIK3C2B gene.
MAP kinase-interacting serine/threonine-protein kinase 1 is an enzyme that in humans is encoded by the MKNK1 gene.
Mitogen-activated protein kinase kinase kinase 4 is an enzyme that in humans is encoded by the MAP3K4 gene.
Mitogen-activated protein kinase 11 is an enzyme that in humans is encoded by the MAPK11 gene.
Cytotrienin A is a secondary metabolite isolated from Streptomyces sp. RK95-74 isolated from soil in Japan in 1997. Cyt A is an ansamycin. Cytotrienin A induces apoptosis on HL-60 cells, as well as inhibiting translation in eukaryotes by inhibiting eukaryotic elongation factor 1A (eEF1A), which can act as an oncogene. These functions lead to the potential of the microbial metabolite acting as an anticancer agent, specifically for blood cancers, as it has proved to be more effective with leukemic cell lines. Cyt A is thought to induce apoptosis by activating c-Jun N-terminal Kinase (JNK), p38 mitogen-activated protein kinase (MAPK), and p36 myelin basic protein (MBP) kinase.
