Macro CK2 accumulation in tenofovir-treated HIV patients is facilitated by CK oligomer stabilization but is not predictive for pathology

Macro-CK type 2 in metastatic prostate cancer

The isoenzyme creatine kinase muscle/brain (CK-MB) still plays an important role for the differential diagnosis of CK elevations and the clarification of their origin from heart or skeletal muscle. Therefore, it is necessary to know the diagnostic pitfalls in interpreting CK-MB results. We demonstrate a case of macro-CK type 2 in a 75-year-old patient with metastatic castration-resistant prostate cancer and its identification by isoenzyme electrophoresis, which can be typical for cancer diseases.

Mitochondrial Proteolipid Complexes of Creatine Kinase

Isoforms of creatine kinase (CK) generate and use phosphocreatine, a concentrated and highly diffusible cellular "high energy" intermediate, for the main purpose of energy buffering and transfer in order to maintain cellular energy homeostasis. The mitochondrial CK isoform (mtCK) localizes to the mitochondrial intermembrane and cristae space, where it assembles into peripherally membrane-bound, large cuboidal homooctamers. These are part of proteolipid complexes wherein mtCK directly interacts with cardiolipin and other anionic phospholipids, as well as with the VDAC channel in the outer membrane. This leads to a stabilization and cross-linking of inner and outer mitochondrial membrane, forming so-called contact sites. Also the adenine nucleotide translocator of the inner membrane can be recruited into these proteolipid complexes, probably mediated by cardiolipin. The complexes have functions mainly in energy transfer to the cytosol and stimulation of oxidative phosphorylation, but also in restraining formation of reactive oxygen species and apoptosis. In vitro evidence indicates a putative role of mtCK in mitochondrial phospholipid distribution, and most recently a role in thermogenesis has been proposed. This review summarizes the essential structural and functional data of these mtCK complexes and describes in more detail the more recent advances in phospholipid interaction, thermogenesis, cancer and evolution of mtCK.