Kelch protein

Kelch motif
Identifiers
Symbol	Kelch_1
Pfam	PF01344
InterPro	IPR006652
SCOP2	1gof / SCOPe / SUPFAM
Available protein structures: Pfam   structures / ECOD   PDB RCSB PDB; PDBe; PDBj PDBsum structure summary PDB 1u6dX:459-504 1zgkA:459-504 1goh :311-357 1gof :311-357 1gog :311-357

Kelch proteins (and Kelch-like proteins) are a widespread group of proteins that contain multiple Kelch motifs. The kelch domain generally occurs as a set of five to seven kelch repeats that form a β-propeller tertiary structure. Kelch-repeat β-propellers are generally involved in protein-protein interactions, though the large diversity of domain architectures and limited sequence identity between kelch motifs make characterisation of the kelch superfamily difficult.

Structure

The N-terminus of several Kelch proteins contain other protein domains, including Discoidin, F-box, and Broad-complex, Tramtrack, Bric-a-Brac/Poxvirus and Zincfinger (BTB/POZ) domains. Kelch proteins may also have only a β-propeller architecture only. The BTB domain of kelch proteins (if present) allows the formation of homo- or heterodimers that mediate protein-protein interactions.

The C-terminus of Kelch proteins contains kelch repeats. Each kelch repeat is a sequence of 44-55 amino acids in length, usually occurring in clusters of 4 - 7 repeats.

Each kelch repeat forms a "blade" of the β-propeller fold, consisting of a four-stranded antiparallel β-sheet secondary structure, arranged radially around a central axis, packed onto its adjoining repeats via hydrophobic contacts.

Kelch-repeat β-propellers undergo a variety of binding interactions with other proteins, notably the actin filaments of a cell.

Function

Kelch like proteins are known to act as substrate adaptors for Cullin 3 ubiquitin ligases.

Organisms

The first Kelch protein (from which this family derives its name) was isolated from Drosophila, in which Kelch-mutant females lay sterile, cup-shaped eggs; "Kelch" is German for "chalice", or "cup". Kelch proteins have also been isolated in many other animals, bacteria, fungi, and even virus (restricted to Poxviridae).

Human proteins containing Kelch motifs

ATRN; ATRNL1; CCIN; ENC1; FBXO42; GAN; HCFC1; HCFC2; IPP; IVNS1ABP; KBTBD10; KBTBD11; KBTBD2; KBTBD3; KBTBD4; KBTBD5; KBTBD6; KBTBD7; KBTBD8; KEAP1; KIAA1900; KLHDC1; KLHDC2; KLHDC3; KLHDC4; KLHDC5; KLHDC6; KLHDC7A; KLHDC7B; KLHDC8A; KLHDC8B; KLHDC9; KLHDC10; KLHL1; KLHL10; KLHL11; KLHL12; KLHL13; KLHL14; KLHL15; KLHL17; KLHL18; KLHL2; KLHL20; KLHL21; KLHL22; KLHL23; KLHL24; KLHL25; KLHL26; KLHL28; KLHL29; KLHL3; KLHL30; KLHL31; KLHL32; KLHL34; KLHL4; KLHL40; KLHL5; KLHL6; KLHL7; KLHL8; KLHL9; LZTR1; MEGF8; MKLN1; RABEPK; SARCOSIN;

References

• Shih-Ching Lo, Xuchu Li, Michael T Henzl, Lesa J Beamer, and Mark Hannink (2006). "Structure of the Keap1:Nrf2 interface provides mechanistic insight into Nrf2 signaling". EMBO J. 25 (15): 3605–3617. doi:10.1038/sj.emboj.7601243. PMC 1538563. PMID 16888629.{{cite journal}}: CS1 maint: multiple names: authors list (link)
• S Zollman, D Godt, G G Privé, J L Couderc, and F A Laski. (1994). "The BTB domain, found primarily in zinc finger proteins, defines an evolutionarily conserved family that includes several developmentally regulated genes in Drosophila". Proc Natl Acad Sci U S A. 91 (22): 10717–10721. doi:10.1073/pnas.91.22.10717. PMC 45093. PMID 7938017.{{cite journal}}: CS1 maint: multiple names: authors list (link)
• J Adams, R Kelso, and L Cooley (2000). "The kelch repeat superfamily of proteins: propellers of cell function". Trends in Cell Biology. 10: 17–24. doi:10.1016/S0962-8924(99)01673-6. PMID 10603472.{{cite journal}}: CS1 maint: multiple names: authors list (link)