PRESENCE OF AN EXTENDED DUPLICATION IN THE PUTATIVE LOW-DENSITY-LIPOPROTEIN RECEPTOR-BINDING DOMAIN OF APOLIPOPROTEIN-B - CLONING AND CHARACTERIZATION OF THE DOMAIN IN SALMON
Pj. Babin et al., PRESENCE OF AN EXTENDED DUPLICATION IN THE PUTATIVE LOW-DENSITY-LIPOPROTEIN RECEPTOR-BINDING DOMAIN OF APOLIPOPROTEIN-B - CLONING AND CHARACTERIZATION OF THE DOMAIN IN SALMON, European journal of biochemistry, 230(1), 1995, pp. 45-51
The sequence of the C-terminal 1058 amino acids of atlantic salmon (Sa
lmo salar) apolipoprotein (apo) B was deduced from the nucleotide sequ
ence of cloned cDNA. In comparison with chicken or mammals apoB-100, s
almon apoB is C-terminally truncated and extended gaps are found. The
two clusters of positively charged residues, previously identified as
part of the putative low-density-lipoprotein (LDL) receptor-binding do
main of apoB, are brought into close proximity in salmon apoB. This is
achieved by the absence between the two clusters of the proline-rich
area with the potential to form an amphipathic beta sheet, present in
higher vertebrates. In addition, analysis of apoB amino acid sequences
currently available in vertebrates revealed the presence of an extend
ed internal duplication in the putative LDL receptor-binding domain. T
hus, the two basic clusters would have been duplicated resulting in th
e presence, except for salmon apoB, of two homologous sites in the C-t
erninal part of the molecule. The results described here together with
earlier biochemical and genetic evidence support the view that Arg350
0, a residue mutated in familial defective apoB-100, could be included
in a folded critical region of the putative LDL receptor-binding doma
in of human apoB-100. This region possibly brings the two sub-domains
that arise from the duplication close to each other.