Kelch protein

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 tandem 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.

Kelch motif
Identifiers
SymbolKelch_1
PfamPF01344
InterProIPR006652
SCOP21gof / SCOPe / SUPFAM

Structure

The N-terminus of several Kelch proteins contain other protein domains, including Discoidin, F-box, and Broad-complex, Tramtrack, Bric-a-Brac/Poxvirus Zinc finger (BTB/POZ) domains. Kelch proteins may also only have a β-propeller architecture. 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;[1] "Kelch" is German for "chalice", or "cup". Kelch proteins have also been isolated in many other animals, plants, 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
  1. UNDERSTANDING THE FUNCTION OF ACTIN-BINDING PROTEINS THROUGH GENETIC ANALYSIS OF DROSOPHILA OOGENESIS, by Andrew M. Hudson and Lynn Cooley; in the Annual Review of Genetics, Vol. 36: 455–488 (Volume publication date December 2002); retrieved 12 December 2013
  • Lo SC, Li X, Henzl MT, Beamer LJ, Hannink M (August 2006). "Structure of the Keap1:Nrf2 interface provides mechanistic insight into Nrf2 signaling". The EMBO Journal. 25 (15): 3605–17. doi:10.1038/sj.emboj.7601243. PMC 1538563. PMID 16888629.
  • Zollman S, Godt D, Privé GG, Couderc JL, Laski FA (October 1994). "The BTB domain, found primarily in zinc finger proteins, defines an evolutionarily conserved family that includes several developmentally regulated genes in Drosophila". Proceedings of the National Academy of Sciences of the United States of America. 91 (22): 10717–21. Bibcode:1994PNAS...9110717Z. doi:10.1073/pnas.91.22.10717. PMC 45093. PMID 7938017.
  • Adams J, Kelso R, Cooley L (January 2000). "The kelch repeat superfamily of proteins: propellers of cell function". Trends in Cell Biology. 10 (1): 17–24. doi:10.1016/S0962-8924(99)01673-6. PMID 10603472.


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