Variants of human L1 cell adhesion molecule arise through alternate splicing of RNA.
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Reid RA, Hemperly JJ
Variants of human L1 cell adhesion molecule arise through alternate splicing of RNA.
J Mol Neurosci. 1992;3(3):127-35.
- PubMed ID
- 1627459 [ View in PubMed]
- Abstract
The L1 cell adhesion molecule was initially identified and characterized in mouse as a cell-surface glycoprotein that mediates neuron-neuron and neuron-Schwann cell adhesion. We have characterized L1 in humans using cDNA structural and mRNA expression analyses. We present the entire coding sequence for human L1, which predicts a 1253-amino acid protein displaying a signal sequence, transmembrane segment, RGD sequence, and potential glycosylation and phosphorylation sites. Nucleotide and deduced amino acid sequence identities between human and mouse L1 are 85% and 87%, respectively. In contrast, the amino acid identity between human L1 and the L1-related molecule chicken Ng-CAM is only 45%. Using Northern blot analyses, a single L1 transcript of 5.5 kb is detected in human fetal brain and in neuroblastoma (IMR-32) and retinoblastoma (Y-79) cell lines. L1 is also expressed in the rhabdomyosarcoma cell lines RD and A-204, which display several muscle characteristics. Two forms of L1, which differ by the presence or absence of a 12-bp cytoplasmic segment, are expressed in both human and mouse. This segment is encoded by a single exon that can be alternately spliced to give rise to the two forms, which appear to be expressed in tissue-specific patterns.