👉 The term "cysteine" is often used to describe a protein that has a sulfur group attached to its side chain. It's a common type of protein in the human body, and it can be found in proteins like collagen, elastin, and keratin. Cysteines are also involved in many cellular processes, including metabolism, cell signaling, and immune function. In terms of the term "cysteine," it is often associated with cystic fibrosis, a