type I K homology (KH) RNA-binding domain found in Mask family proteins
The Mask family includes Drosophila melanogaster ankyrin repeat and KH domain-containing protein Mask, and its mammalian homologues Mask1/ANKHD1 and Mask2/ANKRD17. Mask, also called multiple ankyrin repeat single KH domain-containing protein, is a large ankyrin repeat and KH domain-containing protein involved in Drosophila receptor tyrosine kinase signaling. It acts as a mediator of receptor tyrosine kinase (RTK) signaling and may act either downstream of MAPK or transduce signaling through a parallel branch of the RTK pathway. Mask is required for the development and organization of indirect flight muscle sarcomeres by regulating the formation of M line and H zone and the correct assembly of thick and thin filaments in the sarcomere. Mask1/ANKHD1, also called HIV-1 Vpr-binding ankyrin repeat protein, or multiple ankyrin repeats single KH domain, or Hmask, is highly expressed in various cancer tissues and is involved in cancer progression, including proliferation and invasion. Mask2/ANKRD17, also called ankyrin repeat protein 17, or gene trap ankyrin repeat protein (GTAR), or serologically defined breast cancer antigen NY-BR-16, is a ubiquitously expressed ankyrin factor essential for the vascular integrity during embryogenesis. It may be directly involved in the DNA replication process and play pivotal roles in cell cycle and DNA regulation. It is also involved in innate immune defense against bacteria and viruses.