K homology RNA-binding domain, PCBP_like. Members of this group possess KH domains in a tandem arrangement. Most members, similar to the poly(C) binding proteins (PCBPs) and Nova, containing three KH domains, with the first and second domains, which are represented here, in tandem arrangement, followed by a large spacer region, with the third domain near the C-terminal end of the protein. The poly(C) binding proteins (PCBPs) can be divided into two groups, hnRNPs K/J and the alphaCPs, which share a triple KH domain configuration and poly(C) binding specificity. They play roles in mRNA stabilization, translational activation, and translational silencing. Nova-1 and Nova-2 are nuclear RNA-binding proteins that regulate splicing. This group also contains plant proteins that seem to have two tandem repeat arrrangements, like Hen4, a protein that plays a role in AGAMOUS (AG) pre-mRNA processing and important step in plant development. In general, KH binds single-stranded RNA or DNA. It is found in a wide variety of proteins including ribosomal proteins, transcription factors and post-transcriptional modifiers of mRNA.

Alpha-N-acetylglucosaminidase (NAGLU) N-terminal domain. Alpha-N-acetylglucosaminidase, a lysosomal enzyme required for the stepwise degradation of heparan sulfate. Mutations on the alpha-N-acetylglucosaminidase (NAGLU) gene can lead to Mucopolysaccharidosis type IIIB (MPS IIIB; or Sanfilippo syndrome type B) characterized by neurological dysfunction but relatively mild somatic manifestations. The structure shows that the enzyme is composed of three domains. This N-terminal domain has an alpha-beta fold.

WRC. The WRC domain, named after the conserved Trp-Arg-Cys motif, contains two distinctive features: a putative nuclear localisation signal and a zinc-finger motif (C3H). It is suggested that the WRC domain functions in DNA binding.

Alpha-N-acetylglucosaminidase (NAGLU) tim-barrel domain. Alpha-N-acetylglucosaminidase, a lysosomal enzyme required for the stepwise degradation of heparan sulfate. Mutations on the alpha-N-acetylglucosaminidase (NAGLU) gene can lead to Mucopolysaccharidosis type IIIB (MPS IIIB; or Sanfilippo syndrome type B) characterized by neurological dysfunction but relatively mild somatic manifestations. The structure shows that the enzyme is composed of three domains. This central domain has a tim barrel fold.

Alpha-N-acetylglucosaminidase (NAGLU) C-terminal domain. Alpha-N-acetylglucosaminidase, a lysosomal enzyme required for the stepwise degradation of heparan sulfate. Mutations on the alpha-N-acetylglucosaminidase (NAGLU) gene can lead to Mucopolysaccharidosis type IIIB (MPS IIIB; or Sanfilippo syndrome type B) characterized by neurological dysfunction but relatively mild somatic manifestations. The structure shows that the enzyme is composed of three domains. This C-terminal domain has an all alpha helical fold.