Protein or the physical region of the protein that participates in chemical catalysis. In solution proteins also undergo variation in structure through thermal vibration and the collision with other molecules. Proteins can be informally divided into three main classes, which correlate with typical tertiary structures: globular proteins, fibrous proteins, and membrane proteins. Almost all globular proteins are soluble and many are enzymes. Fibrous proteins are often structural, such as collagen, the major component of connective tissue, or keratin, the protein component of hair and nails. Membrane proteins often serve as receptors or provide channels for polar or charged molecules to pass
HHV capsid portal protein HHV capsid portal protein HHV Capsid Portal Protein, or HSV-1 U-6 protein, is the protein which forms a cylindrical portal in the capsid of Herpes simplex virus (HSV-1). The protein is commonly referred to as the "HSV-1 U-6" protein because it is the transcription product of Herpes gene U-6. The Herpes viral DNA enters and exits the capsid via the capsid portal. The capsid portal is formed by twelve copies of portal protein arranged as a ring; the proteins contain a leucine zipper sequence of amino acids which allow them to adhere to each other. Each icosahedral capsid contains a