The cortactin or HS1 repeat is a tandem repeat of 37-amino acid actin-binding domains. The repeat is named after human cortactin and HS1, proteins involved in cytoskeletal rearrangements implicated in cell migration and apoptosis, respectively. Cortactin contains 6.5 tandem copies of the repeat and is conserved among metazoans, although e.g. insect cortactin and splice variants contain fewer copies. Hematopoietic lineage cell specific protein 1 (HS1) contains 3.5 tandem copies of the cortactin repeat and is mainly expressed in hematopoietic cells. Both cortactin and HS1 contain a C-terminal SH3 domain (see <PDOC50002>). The cortactin repeat domain binds filamentous actin (F-actin) in proteins that modulate the assembly of the actin cytoskeleton. Secondary structure predictions indicate that the cortactin repeat could exhibit a helix-turn-helix structure [1,2,3].

Some proteins known to contain a cortactin repeat domain:

• Mammalian cortactin or oncogene EMS1 protein, a regulator of cytoskeleton remodeling by promoting actin-related protein (Arp)2/3 mediated actin polymerization.
• Human hematopoietic lineage cell specific protein 1 (HS1), a substrate of intracellular protein tyrosine kinases, implicated in the immune response to extracellular stimuli and in cell differentiation induced by cytokines. HS1 is conserved among vertebrates.

The profile we developed covers the entire cortactin repeat and has been manually adapted to detect the partially matching region of C-terminal copies.