Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Pages: 38. Chapters: Aconitase, Activating transcription factor 2, Crystallin, Cytochrome c, Dihydrolipoamide dehydrogenase, Enolase, ESCRT, Fructose-bisphosphate aldolase, Galactokinase, Glutamate racemase, GroEL, Hexokinase, HSP60, MAPK1, Phosphofructokinase, Presenilin, Protein moonlighting, Pyruvate carboxylase, STAT3, Thioredoxin. Excerpt: Protein moonlighting (or gene sharing) is a phenomenon by which a protein can perform more than one function. Ancestral moonlighting proteins originally possessed a single function but through evolution, acquired additional functions. Many proteins that moonlight are enzymes; others are receptors, ion channels or chaperones. The most common primary function of moonlighting proteins is enzymatic catalysis, but these enzymes have acquired secondary non-enyzmatic roles. Some examples of functions of moonlighting proteins secondary to catalysis include signal transduction, transcriptional regulation, apoptosis, motility, and structural. Protein moonlighting may occur widely in nature. Protein moonlighting through gene sharing differs from the use of a single gene to generate different protein by alternative RNA splicing, DNA rearrangement, or post-translational processing. It is also different from multifunctionality of the protein, in which the protein has multiple domains, each serving a different function. Protein moonlighting by gene sharing means that a gene may acquire and maintain a second function without gene duplication and without loss of the primary function. Such genes are under two or more entirely different selective constraints. Various techniques have been used to reveal moonlighting functions in proteins. The detection of a protein in unexpected locations within cells, cell types, or tissues may suggest that a protein has a moonlighting function. Furthermore, sequence or structure...