Origin and evolution of the adaptive immune system: genetic events and selective pressures - PubMed (original) (raw)

Figure 4. The major histocompatibility complex paralogy group and the neurotrophin paralogy group in the human genome

Four sets of major histocompatibility complex (MHC) paralogons are located on chromoso mes 1, 6, 9 and 19 (ReFS 55,137,138). A number of smaller-sized MHC paralogons, which presumably originated from fragmentation and subsequent translocation of the major paralogons, have been identified. Among them, those located on 15q13-q26 and 5q11–q23 seem to have broken off from the paralogons on chromosomes 6 and 9, respectively. Four sets of major neurotrophin paralogons are located on chromosomes 1, 11, 12 and 19 (REF. 89).The MHC paralogy group (right) and neurotrophin paralogy group (left) are thought to have descended from neighbouring regions on a single ancestral chromosome. Paralogues that are distributed across the two paralogy groups are indicated by blue highlighted text. In addition to genes that share paralogues among the relevant paralogons, immunologically important genes, such as those encoding MHC class I, MHC class II, T cell receptors (TCRs), and immunoglobulins (Igs) are shown. A2M, α2-macroglobulin; B2M, β2-microglobulin; BCL, B cell leukaemia/lymphoma; CSK, cytoplasmic tyrosine kinase; CTS, cathepsin; ERAP, endoplasmic reticulum aminopeptidase; IL12RB, interleukin 12 receptor, β-subunit; JAK, Janus kinase; KIR, killer Ig-like receptor; LAG3, lymphocyte activation gene 3; LGMN, legumain; LRC, leukocyte receptor complex; MAP2K, mitogen-activated protein kinase kinase; MATK, megakaryocyte-associated tyrosine kinase; NFKBIA, nuclear factor-κB inhibitor; NKC, natural killer complex; NKR, NK receptor; NRAS, neuroblastoma RAS; PD, programmed cell death 1 ligand; PIAS, protein inhibitors of activated STAT; PIK3R, phosphatidylinositol 3-kinase, regulatory subunit; PSMB, proteasome subunits, β-type; PSME, proteasome activator subunits; RFX, regulatory factor X; RXR, retinoid X receptor; SPI1, spleen focus forming virus proviral integration oncogene; TAP, transporter associated with antigen processing; TAPBP, TAP-binding protein (also known as tapasin); TAPBPL, TAPBP-like; TAPL, TAP-like (also known as ABCB9); TICAM, TIR domain-containing adaptor molecule; TNFSF, tumour necrosis factor ligand superfamily; WGD, whole-genome duplication.