Heat shock protein 27 (Hsp27), also known as heat shock protein beta-1 (HspB1), is a member of the small heat shock protein (sHSP) family that is upregulated during conditions of cellular stress including heat shock, radiation, hypoxia, and exposure to reactive oxygen species (ROS). It is composed of an N-terminal domain, a highly conserved alpha-crystallin domain, and a C-terminal domain. Hsp27 functions as a molecular chaperone to prevent protein aggregation in an ATPase-independent manner. This chaperone activity is altered by changes in oligomerization state or by post-translational modifications including phosphorylation at serine residues 15 and 82, which increases affinity for damaged polypeptides in response to heat shock. Hsp27 also works in complex with other chaperone proteins, such as Hsp70 (Item Nos. 22739 | 23002), to correct misfolded proteins. This protein also plays a role in apoptosis, proteasome activation, cell differentiation, and has been shown to interact with actin and intermediate filaments. Mutations in HSPB1 have been linked to hereditary neuromuscular diseases and cause Charcot-Marie-Tooth Disease Type 2 (CMT-2).
