The long and the short isoform of cell-CAM 105 show variant-specific modifications in adult rat organs.

The cell adhesion molecule cell-CAM 105 is a member of the carcinoembryonic antigen (CEA)-gene family and expressed on the cell surface at least as a long (L-) and a short (S-) isoform. We have developed anti-peptide antisera to investigate the expression patterns of both cell-CAM 105 variants in rat organs. In immunohistochemistry the S- and the L-isoform were co-localized in every tissue investigated. In contrast, the quantification of both isoforms in rat organs by a sandwich-ELISA revealed several differences in their relative expression ratio if compared to the liver value. In submandibular gland and seminal vesicle a significant increase of the S-isoform was found, whereas in kidney the L-isoform was overexpressed. In immunoblot analysis of kidney and seminal vesicle the two isoforms did not appear with the Mr difference which is deduced from their primary structures, suggesting that the two cell-CAM 105 variants are subjected in these tissues to different post translational modifications.