CTX, a novel molecule specifically expressed on the surface of cortical thymocytes in Xenopus

Eur J Immunol. 1996 Apr;26(4):780-91. doi: 10.1002/eji.1830260409.


CTX, a novel developmentally regulated type-I transmembrane protein is expressed specifically by a large fraction of cortical thymocytes in the amphibian Xenopus. This apparently monomeric 55-kDa glycoprotein is composed of two immunoglobulin domains, one variable (V) and one constant (C2 type), followed by a transmembrane and a 64-amino acid cytoplasmic domain. The first immunoglobulin domain is a V-J segment that is generated without gene rearrangement. In the genome, the V and C2 domains are both encoded by two half-domain exons. Two CTX loci are found per haploid genome, and they exhibit sequence differences with a high replacing/silent ratio in the CDR1-like region of the V domain, suggesting that these differences were selected. The cytoplasmic domain contains a motif that is highly conserved evolutionarily in several types of proteins, including adenylyl cyclases. Based on its unique tissue distribution, the variability of its V region and the motif of its cytoplasmic domain, CTX is a candidate for a new type of specific molecule involved in thymocyte selection.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Antibodies, Monoclonal / immunology
  • Antigens, Differentiation, T-Lymphocyte
  • Antigens, Surface / biosynthesis*
  • Base Sequence
  • Biomarkers
  • Clonal Deletion
  • Consensus Sequence
  • DNA, Complementary / genetics
  • Exons / genetics
  • Gene Rearrangement, T-Lymphocyte
  • Genes
  • Membrane Proteins / biosynthesis
  • Membrane Proteins / chemistry
  • Membrane Proteins / genetics
  • Membrane Proteins / isolation & purification*
  • Mice
  • Mice, Inbred BALB C
  • Molecular Sequence Data
  • Polymorphism, Genetic
  • Protein Conformation
  • Sequence Alignment
  • Sequence Homology, Amino Acid
  • Signal Transduction
  • T-Lymphocytes / metabolism*
  • Thymus Gland / metabolism*
  • Xenopus Proteins*
  • Xenopus laevis / metabolism*


  • Antibodies, Monoclonal
  • Antigens, Differentiation, T-Lymphocyte
  • Antigens, Surface
  • Biomarkers
  • DNA, Complementary
  • Membrane Proteins
  • Xenopus Proteins
  • ctx-A protein, Xenopus

Associated data

  • GENBANK/U43330
  • GENBANK/U43393
  • GENBANK/U43394
  • GENBANK/U43395