Sialyltransferase 4C (SIAT4C)

Synthesis of alpha-2,3-linked sialic acid to Gal(beta-1,3)GalNAc is mediated by at least 3 distinct beta-galactoside alpha-2,3-sialyltransferases, including ST3GAL4. Previous characterization of ST3GAL4 cDNAs revealed that the gene produces at least 3 transcripts in human placenta that code for identical proteins except at the 5-prime ends. Further screening for clones that contained the 5-prime end of the cDNA identified 2 additional distinct mRNAs that are expressed in human placenta. Comparison of the genomic DNA sequence with that of the 5 different mRNAs indicated that these transcripts are produced by a combination of alternative splicing and alternative promoter utilization. 1 of them is specifically expressed in placenta, testis, and ovary, indicating that its expression is independently regulated from the others.