A molecule in teleost fish, related with human MHC-encoded G6F, has a cytoplasmic tail with ITAM and marks the surface of thrombocytes and in some fishes also of erythrocytes

Ohashi, K., Takizawa, F., Tokumaru, N., Nakayasu, C., Toda, H., Fischer, U., Moritomo, T., Hashimoto, K., Nakanishi, T., and Dijkstra, J.M.
Immunogenetics   62(8): 543-559 (Journal)
Registered Authors
Ohashi, Ken
MHC, G6F, ITAM, thrombocyte, erythrocyte, fish
MeSH Terms
  • Amino Acid Sequence
  • Animals
  • Blood Platelets/immunology
  • Chromosome Mapping
  • Erythrocytes/immunology
  • Evolution, Molecular
  • Fish Proteins/chemistry
  • Fish Proteins/genetics*
  • Fish Proteins/immunology*
  • Fishes/genetics*
  • Fishes/immunology*
  • GATA1 Transcription Factor/genetics
  • Gene Expression
  • Goldfish/genetics
  • Goldfish/immunology
  • Humans
  • Immunoglobulins/chemistry
  • Immunoglobulins/genetics*
  • Major Histocompatibility Complex*
  • Molecular Sequence Data
  • NF-E2 Transcription Factor/genetics
  • Oncorhynchus mykiss/genetics
  • Oncorhynchus mykiss/immunology
  • Oryzias/genetics
  • Oryzias/immunology
  • Sequence Homology, Amino Acid
  • Species Specificity
20614118 Full text @ Immunogenetics

In teleost fish, a novel gene G6F-like was identified, encoding a type I transmembrane molecule with four extracellular Ig-like domains and a cytoplasmic tail with putative tyrosine phosphorylation motifs including YxN and an immunoreceptor tyrosine-based activation motif (ITAM). G6F-like maps to a teleost genomic region where stretches corresponding to human chromosomes 6p (with the MHC), 12p (with CD4 and LAG-3), and 19q are tightly linked. This genomic organization resembles the ancestral “Ur-MHC” proposed for the jawed vertebrate ancestor. The deduced G6F-like molecule shows sequence similarity with members of the CD4/LAG-3 family and with the human major histocompatibility complex-encoded thrombocyte marker G6F. Despite some differences in molecular organization, teleost G6F-like and tetrapod G6F seem orthologous as they map to similar genomic location, share typical motifs in transmembrane and cytoplasmic regions, and are both expressed by thrombocytes/platelets. In the crucian carps goldfish (Carassius auratus auratus) and ginbuna (Carassius auratus langsdorfii), G6F-like was found expressed not only by thrombocytes but also by erythrocytes, supporting that erythroid and thromboid cells in teleost fish form a hematopoietic lineage like they do in mammals. The ITAM-bearing of G6F-like suggests that the molecule plays an important role in cell activation, and G6F-like expression by erythrocytes suggests that these cells have functional overlap potential with thrombocytes.

Genes / Markers
Mutations / Transgenics
Human Disease / Model
Sequence Targeting Reagents
Engineered Foreign Genes