cl00098

KH-II (K homology RNA-binding domain, type II). KH binds single-stranded RNA or DNA. It is found in a wide variety of proteins including ribosomal proteins (e.g. ribosomal protein S3), transcription factors (e.g. NusA_K), and post-transcriptional modifiers of mRNA (e.g. hnRNP K). There are two different KH domains that belong to different protein folds, but they share a single KH motif. The KH motif is a beta-alpha-alpha-beta-beta unit that folds into an alpha-beta structure with a three stranded beta-sheet interupted by two contiguous helices. In addition to their KH core domain, KH-II proteins have an N-terminal alpha helical extension while KH-I proteins have a C-terminal alpha helical extension.