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),[3] and the yeast kinase TOR1.[4] 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.

Quick Facts Identifiers, Symbol ...
HEAT repeat
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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 PDB: 2IAE.[1][2]
Identifiers
SymbolHEAT
PfamPF02985
InterProIPR000357
PROSITEPDOC50077
SCOP21b3u / SCOPe / SUPFAM
Available protein structures:
Pfam  structures / ECOD  
PDBRCSB PDB; PDBe; PDBj
PDBsumstructure summary
PDB1b3u, 1f59, 1gcj, 1ibr, 1m5n, 1o6o, 1o6p, 1qbk, 1qgr, 1u6g, 1ukl, 2bku
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Various HEAT repeat proteins and their structures

Representative examples of HEAT repeat proteins include importin β (also known as karyopherin β) family,[5] regulatory subunits of condensin and cohesin,[6] separase,[7] PIKKs (phosphatidylinositol 3-kinase-related protein kinases) such as ATM (Ataxia telangiectasia mutated) and ATR (Ataxia telangiectasia and Rad3 related),[8][9] and the microtubule-binding protein XMAP215/Dis1/TOG[10] and CLASP.[11] Thus, cellular functions of HEAT repeat proteins are highly variable.

The structure of the following HEAT repeat proteins have been determined so far:

References

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