Tetratricopeptide

The tetratricopeptide repeat (TPR) is a structural motif. It consists in a degenerate 34 amino acid sequence motif identified in a wide variety of proteins. It is found in tandem arrays of 3–16 motifs, which form scaffolds to mediate protein–protein interactions and often the assembly of multiprotein complexes. TPR-containing proteins include the anaphase-promoting complex (APC) subunits cdc16, cdc23 and cdc27, the NADPH oxidase subunit p67-phox, hsp90-binding immunophilins, transcription factors, the PKR protein kinase inhibitor, the major receptor for peroxisomal matrix protein import PEX5 and mitochondrial import proteins.

Structure
The structure of the PP5 protein was the first structure to be determined. The structure solved by X-ray crystallography by Das and colleagues showed that the TPR sequence motif was composed of a pair of antiparallel alpha helices. The PP5 structure contained 3 tandem TPR repeats which showed the sequential TPR repeats formed an alpha-helical solenoid structure.

Examples
Human genes encoding proteins containing this motif include:
 * AAG2, ANAPC7
 * BBS4
 * CABIN1, CDC16, CDC23, CDC27, CNOT10, CTR9
 * DNAJC3, DNAJC7, DYX1C1
 * FAM10A4, FAM10A5, FKBP4, FKBP5, FKBP8, FKBPL
 * GPSM1, GPSM2, GTF3C3
 * IFIT1, IFIT1L, IFIT2, IFIT3, IFIT5, IFT88
 * KLC1, KLC2, KLC3, KLC4, KNS2
 * LONRF2
 * NARG1, NARG1L, NASP, NCF2, NFKBIL2, NOXA1, NPHP3
 * OGT
 * PEX5, PEX5L, PPID, PPP5C, PRPF6
 * RANBP2, RANBP2L2, RANBP2L6, RAPSN, RGPD5, RGPD7, RPAP3
 * SGTA, SGTB, SH3TC1, SH3TC2, SPAG1, SRP72, ST13, STIP1, STUB1, SUGT1
 * TMTC1, TMTC2, TMTC3, TMTC4, TOMM34, TOMM70A
 * TTC1, TTC3, TTC4, TTC5, TTC6, TTC7A, TTC7B, TTC8, TTC9C, TTC12, TTC13, TTC14, TTC15, TTC16, TTC17, TTC18, TTC21A, TTC21B, TTC22, TTC24, TTC25, TTC27, TTC28, TTC29, TTC30A, TTC30B, TTC31, TTC33, TTC37
 * UNC45A, UNC45B, UTX, UTY
 * WDTC1
 * ZC3H7B