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Phylogeny of Antigen-Processing Enzymes: Cathepsins of a Cephalochordate, an Agnathan and a Bony Fish (2003)

Uinuk-ool, T. S. ; Takezaki, N. ; Kuroda, N. ; [et al.]

Oxford, UK : Blackwell Science Ltd

Scandinavian journal of immunology 58 (2003), S. 0

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ISSN: 1365-3083

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Medicine

Notes: Cathepsins are enzymes that have been cleaving peptide bonds of lysosomal proteins probably since lysosomes appeared in early eucaryotes. When the adaptive system emerged in gnathostomes, cathepsins were recruited to produce peptides for loading onto the major histocompatibility complex class II molecules and for degrading the class II-associated invariant chain just before the loading. The circumstances under which this recruitment took place are unclear because the knowledge about vertebrate cathepsins is limited largely to mammals. To shed light on the recruitment, 10 amphioxus, one lamprey and one cichlid fish cathepsin cDNA clone were characterized and analysed phylogenetically. Disregarding cathepsin O, whose phylogenetic position is uncertain, the analysis confirms the existence of two old lines of descent, the B and the L lineages of cathepsins, which diverged from each other early in the evolution of eucaryotes. The B lineage encompasses cathepsins B, C and Z (X). The L lineage splits off sublineages encompassing cathepsins F and W before the plant–animal separation and cathepsin H early in the evolution of the metazoa. The remaining cathepsins belonging to the L lineage diverged from one another during the evolution of vertebrates: S, K and L before the emergence of bony fishes, and the group of rodent placentally expressed cathepsins [J (P), M, Q, R, 3, 6, 7 and 8] as well as the testis/ova-expressed cathepsins (testins) probably after the divergence of rodents from primates. The part possibly played by the adaptive immune system in some of these divergences is discussed.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1046/j.1365-3083.2003.01322.x

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Molecular cloning and linkage analysis of complement C3 and C4 genes of the Japanese medaka fish (2000)

Kuroda, N. ; Naruse, K. ; Shima, A. ; [et al.]

Springer

Immunogenetics 51 (2000), S. 117-128

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ISSN: 1432-1211

Keywords: Key words Complement ; C3 ; C4 ; Medaka fish ; Linkage analysis

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Medicine

Notes: Abstract The thioester-containing complement components, C3 and C4, are believed to have arisen by gene duplication from a common ancestor, and the mammalian C4 gene resides in the vicinity of the C2 and B genes within the major histocompatibility complex (MHC) class III region. To analyze the evolution of both the complement system and the MHC, we determined the complete primary structures of two C3 genes, termed Orla C3-1 and Orla C3-2, and one C4 gene, termed Orla C4, of a teleost, Japanese medaka fish (Oryzias latipes), by analyzing cDNA clones isolated from a liver library constructed using the inbred AA2 strain. The deduced basic structures of Orla C3-1, C3-2, and C4, such as the subunit chain structure, the thioester site, and the proteolytic activation site, are similar to their mammalian counterparts. However, the catalytic His residue which greatly increases the rate of thioester reaction, is replaced by Ala in Orla C3-2, implying functional differentiation between two C3 molecules. Mapping analysis revealed a close linkage between the C3-1 and C3-2 genes, indicating that they arose by a local duplication rather than by a genome-wide tetraploidization. The C4 gene belongs to a different linkage group, and no linkage was observed among the C3, C4, Bf/C2, MHC class I, and MHC class II loci. These results suggest that the MHC class III complement region was established in the tetrapod lineage, or lost in the teleost lineage.