Defects of RNA catabolism are implicated in a number of pathologic states, including chronic inflammation and autoimmune and neoplastic diseases. Beyond viral biology and the development of antiviral therapies or vaccines, the study of gammaherpesvirus-induced shutoff has the potential to further elucidate cellular pathways that regulate mRNA accumulation, and how disruption of such pathways may contribute to disease. It can also cause severe Niltubacin invasive diseases such as sepsis, necrotizing fasciitis and toxic shock syndrome, as well as complications post infection such as rheumatic fever and glomerulonephritis. Surface structures of S. pyogenes allow the bacteria to XAV939 adhere to, colonize and invade mucus membranes and human skin. Some of these structures are M protein, M-like proteins, collagen type I-binding protein and streptococcal fibronectin-binding protein I. Mammalian cells have a variety of ways to detect invading pathogens and to alert the immune system. The best known are the Toll-like receptors, which are transmembrane receptors containing an extracellular leucine rich repeat domain. It is the LRR domain in TLRs that is responsible for recognizing diverse microbial components. More recently indentified receptors involved in bacterial recognition are receptors with a carboxyl-terminal LRR domain, a central nucleotide binding and oligomerization domain. They are implicated in the cytosolic detection of bacterial components, mediated through the LRR domain. LRR proteins are also involved in proteinprotein interactions such as signal transduction, cell adhesion and apoptosis. LRR proteoglycan decorin has been shown to bind to fibrillar collagens. Other examples of LRR proteins are proline arginine-rich end leucine-rich repeat protein, chondroadherin and biglycan. LRRs are typically 20�C30 amino acids long and the defining feature of the LRR motif is an 11-residue sequence LxxLxLxxNxL. The number of LRR repeats ranges from 2 to 45 and they are divided into a conserved and variable segment. The conserved amino-terminal stretch of 9�C12 amino acids forms the b-strand and the variable segment is a carboxy-terminal stretch of 10�C19 amino acids that varies in length, sequence and structure. The arrangement of the repeats results in a horseshoe-shaped structure with the b-sheet on the concave side and the variable stretches on the convex side. Several pathogenic bacteria, both Gram positive and Gram negative express surface proteins with LRR regions. LRR proteins have also been identified in viruses, archaea and eukaryotes. Internalins of Listeria monocytogenes are the most studied bacterial proteins with LRR domains. There are at least 9 proteins in this family and all have been implicated in the invasion of the human cell. The streptococcal leucine rich protein is predicted to be a lipoprotein attached to the cell membrane and has been shown to be camouflaged for antibody recognition by the M6 protein.