KDa in the context of SI Brochure

Actin is a family of globular multi-functional proteins that form microfilaments in the cytoskeleton, and the thin filaments in muscle fibrils. It is found in essentially all eukaryotic cells, where it may be present at a concentration of over 100 μM; its mass is roughly 42 kDa, with a diameter of 4 to 7 nm.

An actin protein is the monomeric subunit of two types of filaments in cells: microfilaments, one of the three major components of the cytoskeleton, and thin filaments, part of the contractile apparatus in muscle cells. It can be present as either a free monomer called G-actin (globular) or as part of a linear polymer microfilament called F-actin (filamentous), both of which are essential for such important cellular functions as the mobility and contraction of cells during cell division.

Prorenin (/prəˈriːnɪn/) is a protein that constitutes a precursor for renin, the hormone that activates the renin–angiotensin system, which serves to raise blood pressure. Prorenin is converted into renin by the juxtaglomerular cells, which are specialised smooth muscle cells present mainly in the afferent, but also the efferent, arterioles of the glomerular capillary bed.

Prorenin is a relatively large molecule, weighing approximately 46 KDa.

Resistin, also known as adipose tissue-specific secretory factor (ADSF) or C/EBP-epsilon-regulated myeloid-specific secreted cysteine-rich protein (XCP1), is a cysteine-rich peptide hormone that is derived from adipose tissue and, in humans, is encoded by the RETN gene.

In primates, pigs, and dogs, resistin is secreted primarily by immune and epithelial cells, whereas in rodents, it is mainly secreted by adipose tissue. The human resistin pre-peptide consists of 108 amino acid residues, while in mice and rats it is 114 amino acids in length; the molecular weight is approximately 12.5 kDa. Resistin is classified as an adipose-derived hormone (similar to a cytokine), and its physiological role has been widely debated, particularly regarding its involvement in obesity and type II diabetes mellitus (T2DM).

Cytokines (/ˈsaɪtəkaɪn/) are a broad and loose category of small proteins (~5–25 kDa) important in cell signaling. Cytokines are produced by a broad range of cells, including immune cells, as well as endothelial cells, fibroblasts, and various types of connective tissue cells. A single cytokine may be produced by more than one type of cell.

Cytokines are usually too large to cross cell membranes and enter cells. They typically function by interacting with specific cytokine receptors on the surface of target cells. Cytokines include chemokines, interferons, interleukins, lymphokines, and tumour necrosis factors, but generally not hormones or growth factors (despite some overlap in the terminology).

RNA polymerase II (RNAP II and Pol II) is a multiprotein complex that transcribes DNA into precursors of messenger RNA (mRNA) and most small nuclear RNA (snRNA) and microRNA. It is one of the three RNAP enzymes found in the nucleus of eukaryotic cells. A 550 kDa complex of 12 subunits, RNAP II is the most studied type of RNA polymerase. A wide range of transcription factors are required for it to bind to upstream gene promoters and begin transcription.