Chemical and Synthetic Biology Approaches to Understand Cellular Functions - Part A, Volume 621, the latest release in the Methods in Enzymology series, highlights new advances in the field, with this volume covering Site-directed ethylation of membrane proteins for measuring conformational transitions in lipid bilayers, the Design and synthesis of fluorescent activity probes for protein phosphatases, Stains, Utilizing split-nanoLuc fragments as luminescent probes for protein solubility in living cells, SH2-domain based sensor for intracellular recognition of sulfo-tyrosine, DNA-encoded immunoglobulins for detection of parasites, An engineered TEV protease – calmodulin fusion based sensor for neuronal calcium recording, and much more.