Molecular characterization of apolipoprotein A-I from the skin mucosa of Cyprinus carpio

Apolipoprotein a-i is the most abundant protein in cyprinus carpio plasma that plays an important role in lipid transport and protection of the skin by means of its antimicrobial activity. a 527 bp cdna fragment encoding c terminus part of apoa-i from the skin mucosa of common carp was isolated using rt-pcr. after genbank database searching,a partial sequence containing a coding sequence (cds) relating to this gene was found. overlapping of the cdna fragment with this cds allowed us to obtain the full-length sequence including non-coding regions. this sequence has 1170bp including a polya tail of 18 bp plus 45 and 354 bp at the 3′- and 5′- untranslatedregions,respectively. the complete sequence contained an open reading frame of 256 amino containing 5 amino acid propeptides with a predicted molecular mass of 29.967 kda and theoretical pi of 6.13. the signal peptide of common carp apoa-i was predicted to have the most likely cleavage site between amino acid positions 17 and 18. domain analysis of common carp apoa-i showed the conserved domain of apolipoprotein a1/a4/e between amino acid resides 67 to 251. the similarity search indicated that common carp apoa-i matched apoa protein from the group of fish with 45-77% similarity,but showed relatively low levels of similarity to its mammalian counterparts (20-28%).it was shown that the secondary structure of c. carpio apoa-i consisted of α-helical predominantly amphipathic in nature and was characterized by the presence of thirteen conserved repeats.