An example of an alpha solenoid structure composed of 15 HEAT repeats. The protein phosphatase 2A regulatory subunit is shown with the N-terminus in blue at bottom and the C-terminus in red at top. A single helix-turn-helix motif is shown in the center with the outer helix in pink, the inner helix in green, and the turn in white. From .
|SCOPe||1b3u / SUPFAM|
A HEAT repeat is a protein tandem repeat structural motif composed of two alpha helices linked by a short loop. HEAT repeats can form alpha solenoids, a type of solenoid protein domain found in a number of cytoplasmic proteins. The name "HEAT" is an acronym for four proteins in which this repeat structure is found: Huntingtin, elongation factor 3 (EF3), protein phosphatase 2A (PP2A), and the yeast kinase TOR1. HEAT repeats form extended superhelical structures which are often involved in intracellular transport; they are structurally related to armadillo repeats. The nuclear transport protein importin beta contains 19 HEAT repeats.
- Cho, Uhn Soo; Xu, Wenqing (1 November 2006). "Crystal structure of a protein phosphatase 2A heterotrimeric holoenzyme". Nature. 445 (7123): 53–57. doi:10.1038/nature05351. PMID 17086192.
- Groves MR, Hanlon N, Turowski P, Hemmings BA, Barford D (January 1999). "The structure of the protein phosphatase 2A PR65/A subunit reveals the conformation of its 15 tandemly repeated HEAT motifs". Cell. 96 (1): 99–110. doi:10.1016/S0092-8674(00)80963-0. PMID 9989501.
- Andrade MA, Bork P (October 1995). "HEAT repeats in the Huntington's disease protein". Nat. Genet. 11 (2): 115–6. doi:10.1038/ng1095-115. PMID 7550332.