Gene structure and alternative splicing of murine podocalyxin: a member of the CD34 sialomucin family.

Podocalyxin is a sialoglycoprotein of the glomerular podocytes, vascular endothelial cells, platelets, and hemopoietic stem cells. The function of podocalyxin is unknown, but it contains most of the protein bound sialic acid in the glomerulus and is considered vital in the structure and function of the glomerular filtration apparatus. The murine podocalyxin full-length cDNA has been determined and is 5,318 base pairs. The gene localizes to chromosome 6B1 by FISH analysis and contains eight major exons with one additional alternatively spliced exon. The alternatively spliced isoform of podocalyxin codes for a truncated intracellular domain and is expressed in a tissue specific pattern in parallel with full-length podocalyxin. The organization of the gene structure of murine podocalyxin is similar to the murine CD34 gene and suggests a distant evolutionary relationship to CD34.