Pharmacology Dictionary

Cathepsins are intracellular proteinases that reside within lysosomes or specific intracellular granules. Cathepsins are used to degrade proteins or peptides that are internalised from the extracellular space. Some cathepsins such as cathepsin-Gor cathepsin-Kmay be released from the cell to degrade specific extracellular matrix proteins. All cathepsins except cathepsin-G (serine) and cathepsin-D (aspartyl) are cysteine proteinases.

An episodic sudden loss of postural muscle tone and function, ranging from slight weakness to complete body collapse, due to imbalanced descending monoaminergic and cholinergic modulation of motorneurons.

In human narcolepsy it is, typically triggered by emotionally arousing, appetitive or pleasurable stimuli, such as joy and laughter, or food presentation in animals.

A capsid is a proteinaceous shell encasing the viral genome. Viral capsids are polymeric, ordered structures composed of one or more virus encoded subunits.

Capsaicin, also known as N-Vanillyl-8-methyl-6-(E)- noneamide, is the most pungent of the group of compounds called capsaicinoids: It is a common ingredient in varieties of pepper such as habanero, Thai, tabasco, cayenne etc.

One target with which capsaicin interacts is the capsaicin receptor, an ion channel belonging to the superfamily of TRP channels. Because of the structural relation to other TRP channels and because the vanilloid moiety is an essential component of capsaicin, the capsaicin receptor is also called TRPV1 or vanilloid receptor (VR1). It is involved in heat and pain perception.

Small ubiquitous calcium-binding protein. Calmodulin binds and regulates the activity of many protein targets involved in cellular signal transduction pathways mediated by calcium. Calmodulin is ranked among the most conserved proteins and plays a key role in many cellular processes.

Apeptide hormone rapidly inhibiting osteoclast activity. The relevance of calcitonin in human calcium homeostasis is not well understood. Calcitonin has been used for the treatment of osteoporosis, although due to the availability of more potent drugs with less side effects, and the lack of clear data on the anti-fracture efficacy of calcitonin, its clinical use has been steadily declining.

Calcium-dependent serine/threonine phosphatase (also known as protein phosphatase 2B or PP2B).

Calcineurin is a heterodimer composed of a catalytic subunit (Calcineurin A) and a regulatory subunit that contains an autoinhibitory domain (Calcineurin B). The catalytic subunit also contains a calmodulin-binding domain. Binding of calcium to the regulatory sununit allows the binding of calmodulin to the catalytic subunit, resulting in displacement of the autoinhibitory domain and enzymatic activation.

Calcineurin has many functions within eukaryote cells but is best known for its role in activating transcription of the interleukin 2 (IL-2) gene. IL-2 is required for activation of B- and T- cells and thus calcineruin inhibitors such as cyclosporin A and FK506, are potent immunosuppressants.

Cachexia refers to a physical wasting due to loss of muscle and fat.

Cachexia is often found in end-stage cancer patients but is also caused by autoimmune disorders or by infectious diseases such as AIDS and tuberculosis.

BDNF (brain-derived neurotrophic factor) is a neurotrophin, i.e. a target-derived growth factor, which is expressed in the brain predominantly in the hippocampus.

It acts through its tyrosine kinase receptor, trkB, which after ligand activation induces phosphorylation of intracellular signalling proteins on tyrosine residues.

BDNF expression is suppressed by stress hormones, and increased by antidepressants through a yet unknown mechanism.

The breast cancer resistance protein (BCRP) belongs to the G-branch of the ABC-transporter family (ABCG2). In contrast to most other ABC-proteins, BCRP consists of only one transmembrane domain (TDM) with one nucleotide binding fold (NBF) at its C-terminus.

Because of this structural characteristic BCRP as well as other ABC-transporters with only one TMD are termed half transporters.

To achieve functional activity these transporters have to form hetero- or homodimers.

BCRP is involved in the multidrug resistance of certain tumors and transports endogenous compounds like cholesterol and steroid hormones.