Jumping Translocation Breakpoint Protein (JTB)

The JTB open reading frame encodes a 146-amino acid protein with a 75-amino acid extracellular domain (after removal of the signal sequence), a 21-amino acid transmembrane domain, and a 20-amino acid intracellular domain.

The JTB protein is highly conserved among divergent eukaryotic species. Northern blot analysis showed ubiquitous expression of a 1-kb mRNA, with highest expression in thyroid and skeletal muscle. Kidney and spinal cord expressed an additional transcript of approximately 1.4 kb. The JTB gene contains 5 exons over a length of 3 kb. The jumping translocation resulted in a JTB truncation, which would potentially produce a JTB product devoid of the transmembrane domain. JTB is located in a gene-rich region at 1q21, called the epidermal differentiation complex (EDC).