MOLECULAR-CLONING OF SSD-FORM NEURAL CELL-ADHESION MOLECULES (N-CAMS)AS THE MAJOR FORM IN XENOPUS HEART

Different forms of neural cell adhesion molecule (N-CAM) are generated by alternative splicing of primary transcripts and considered to have distinct biological functions. We cloned cDNAs encoding a new form of N-CAMs from the Xenopus heart cDNA library. Comparison of the sequenc es with chicken and mouse NCAMs revealed that these clones code for ss d-form N-CAM. We demonstrate by Northern blot analysis that the ssd fo rm is the major form expressed in the Xenopus adult heart. We obtained two types of ssd-form N-CAM, which are transcripts from N-CAM 1 and N -CAM 2 genes. Both types contain muscle specific domain (MSD) but not pi domain. Northern blot analysis also indicated that this form is not expressed in adult brain, in which ld-form N-CAM is the main N-CAM ex pressed, It is possible that high levels of specific expression of ssd -form N-CAM. are related with the differentiation of cardiac muscles. (C) 1998 Academic Press.