Protein Phosphatase 1, Regulatory Subunit 21 (PPP1R21)

CCDC128 belongs to the CCDC family. A coiled coil is a structural motif in proteins, in which 2-7 alpha-helices are coiled together like the strands of a rope (dimers and trimers are the most common types). Many coiled coil type proteins are involved in important biological functions such as the regulation of gene expression e.g. transcription factors. Notable examples are the oncoproteins c-fos and jun, and the muscle protein tropomyosin. The possibility of coiled coils for α-keratin was proposed by Francis Crick in 1952 as well as mathematical methods for determining their structure. Remarkably, this was soon after the structure of the alpha helix was suggested in 1951 by Linus Pauling and coworkers. Coiled coils usually contain a repeated pattern, hxxhcxc, of hydrophobic (h) and charged (c) amino-acid residues, referred to as a heptad repeat.