Exostoses Like Protein 3 (EXTL3)

The deduced 919-amino acid EXTL3 protein contains a highly conserved region in the C terminus common to other EXT proteins. Northern blot analysis detected expression of 6.2- and 4.7-kb EXTR1 transcripts in all tissues tested except ovary. The larger transcript was predominant in brain, skeletal muscle, and testis, and the shorter transcript in heart, liver, thymus, and prostate.When the cDNA was introduced into a pancreatic beta-cell line that showed REG-dependent growth, the transformants exhibited a significant increase in the incorporation of 5-prime-bromo-2-prime-deoxyuridine as well as in the cell numbers in response to REG protein. A homology search revealed that the rat REG protein receptor cDNA is a homolog of EXTL3. The rat and human proteins share 97% sequence identity.