|PROSITE documentation PDOC50084 [for PROSITE entry PS50084]|
The K homology (KH) domain was first identified in the human heterogeneous nuclear ribonucleoprotein (hnRNP) K. It is a domain of around 70 amino acids that is present in a wide variety of quite diverse nucleic acid-binding proteins . It has been shown to bind RNA [2,3]. Like many other RNA-binding motifs, KH motifs are found in one or multiple copies (14 copies in chicken vigilin) and, at least for hnRNP K (three copies) and FMR-1 (two copies), each motif is necessary for in vitro RNA binding activity, suggesting that they may function cooperatively or, in the case of single KH motif proteins (for example, Mer1p), independently .
According to structural [2,3,4] analysis the KH domain can be separated in two groups. The first group or type-1 contain a β-α-α-β-β-α structure, whereas in the type-2 the two last β-sheet are located in the N terminal part of the domain (α-β-β-α-α-β). Sequence similarity between these two folds are limited to a short region (VIGXXGXXI) in the RNA binding motif. This motif is located between helice 1 and 2 in type-1 and between helice 2 and 3 in type-2.
Some proteins known to contain a type-1 KH domain are listed below:
Proteins known to contain a type-2 KH domain are listed below:
To identify KH domains we developed two profiles, one specific for type-1 and the other type-2. Both profiles cover the whole domain.Last update:
December 2001 / First entry.
PROSITE methods (with tools and information) covered by this documentation:
|1||Authors||Burd C.G., Dreyfuss G.|
|Title||Conserved structures and diversity of functions of RNA-binding proteins.|
|2||Authors||Musco G., Kharrat A., Stier G., Fraternali F., Gibson T.J., Nilges M., Pastore A.|
|Title||The solution structure of the first KH domain of FMR1, the protein responsible for the fragile X syndrome.|
|Source||Nat. Struct. Biol. 4:712-716(1997).|
|3||Authors||Baber J.L., Libutti D., Levens D., Tjandra N.|
|Title||High precision solution structure of the C-terminal KH domain of heterogeneous nuclear ribonucleoprotein K, a c-myc transcription factor.|
|Source||J. Mol. Biol. 289:949-962(1999).|
|Title||KH domain: one motif, two folds.|
|Source||Nucleic Acids Res. 29:638-643(2001).|