Polymorphism of the untranslated regions of the F3/contactin mRNA in the rat nervous system

Diversity of contactin mRNA in human brain tumors

“…The first sequence contained a leader exon of 151 nt sharing the same 37 nt at the 3′end of the exon with the Contactin mRNA currently reported in GenBank®. These leader exons exhibit high levels of similarities with the proximal exon of the A‐type, as previously reported in the mouse and rat [11,12] and are called A‐151 and A‐37, respectively according to their length. Another leader sequence of 208 nucleotides with significant similarities to the rodent proximal exon of the C‐type was also cloned and called C‐208.…”

“…Exon C‐118 was associated with an insertion cassette between C‐118 and exon 1. This cassette of 139 nucleotides was called Addin‐3 as it spliced at the same location as Addin‐1 and Addin‐2 did, as reported in rat F3/contactin mRNAs [12]. Addin‐3 presented no significant similarities with rat Addin‐1 and Addin‐2.…”

“…No sequence similarity with the mouse exon 0 or exon B has been found in the human genome. Absence of this sequence has already been demonstrated for the rat genome [12]. Rat Addin‐1 and Addin‐2 sequences, which are rat spliced exons within the rat Contactin 5′UTR [12], are not retrieved in the human genome on the basis of sequence similarities.…”

“…Second, Contactin is a natural ligand of both receptor protein tyrosine phosphatase beta (RPTPβ) and tenacins [7–9], which are overexpressed in gliomas [10]. And finally, 5′UTR polymorphisms of F3/contactin mRNA have been demonstrated in both mouse [11] and rat [12] and different proximal exons have already been reported in rodent databases.…”

The mouse F3/contactin glycoprotein

“…91 On the other hand, subsequent expression on accounts to 6.3 Kbp, 27 which, however, undergoes some variability in its 5' untranslated region, depending upon the existence of a complex splicing mechanism within the 5' flanking region. [69][70][71] The above overall organization is shared by further axonal Ig superfamily components, which display a relatively high level of homology to F3/Contactin. Indeed, an about 30% similarity in the aminoacid sequence was found with the transmembrane glycoprotein L1, 23 while a 50% similarity was found with the GPI-anchored Transient Axonal Glycoprotein TAG-1.…”