Variants of human L1 cell adhesion molecule arise through alternate splicing of RNA.
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.
Reid
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RA
Becton Dickinson and Company Research Center, Research Triangle Park, NC 27709-2016.
Hemperly
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D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002448:Cell Adhesion; D015816:Cell Adhesion Molecules, Neuronal / Q000096:biosynthesis / Q000235:genetics*; D004247:DNA / Q000235:genetics; D015870:Gene Expression; D005796:Genes; D014644:Genetic Variation; D006801:Humans; D039841:Leukocyte L1 Antigen Complex; D051379:Mice / Q000235:genetics; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012326:RNA Splicing; D012333:RNA, Messenger / Q000378:metabolism*; D012689:Sequence Homology, Nucleic Acid
D015816:Cell Adhesion Molecules, Neuronal; D039841:Leukocyte L1 Antigen Complex; D012333:RNA, Messenger; D004247:DNA