PMID: 9192786Jun 15, 1997Paper

Organization of the human LU gene and molecular basis of the Lu(a)/Lu(b) blood group polymorphism.

Blood
W El NemerC Le Van Kim

Abstract

The Lutheran (Lu) blood group antigens and the B-cell adhesion molecule (B-CAM) epithelial cancer antigen are carried by recently cloned integral glycoproteins that belong to the Ig superfamily. We have previously shown that the Lu and B-CAM antigens are encoded by the same gene, LU, and that alternative splicing of the primary transcript most likely accounts for the presence of both antigens on two isoforms that differ by the length of their cytoplasmic tails. In the present report, we isolated the human LU gene by cloning a 20-kb HindIII fragment from Lu(a - b+) genomic DNA. The LU gene is organized into 15 exons distributed over 12.5 kb. Alternative splicing of intron 13 generates the 2.5- and 4.0-kb transcript spliceoforms encoding the long tail and the short tail Lu polypeptides, respectively. Sequencing of the major mRNA species (2.5 kb) amplified from human bone marrow, kidney, placenta, and skeletal muscle did not suggest the presence of tissue-specific Lu glycoprotein isoforms. The same transcription initiation point, located 22 bp upstream from the initiation codon, was characterized in several tissues. In agreement with the wide tissue distribution of the Lu messengers, the GC-rich proximal 5' flanking region of the ...Continue Reading

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