Identification of a novel apolipoprotein(a)-related protein from the European hedgehog (Erinaceus europaeus).
We have isolated a cDNA encoding an apo(a)-related protein designated HaRP-1 (Hedgehog apo(a) related protein-1). The HaRP-1 cDNA (2114 bp; corresponding to a 2.6 kb transcript) was isolated from a hedgehog liver cDNA library. The HaRP-1 clone corresponded to an open reading frame of 676 amino acids and contains a signal sequence followed by a preactivation domain and 7 kringle domains which exhibit an average of 57% amino acid identity with hedgehog plasminogen kringle III. We expressed HaRP-1 in human embryonic kidney cells; immunoprecipitation of metabolically-labeled conditioned medium from transfected cells showed the presence of a 74 kDa band corresponding to HaRP-1. Of note, we also observed an approximately 72 kDa species present in hedgehog plasma by western blotting using a human anti-apo(a) monoclonal antibody; we speculate that the 72 kDa plasma species corresponds to HaRP-1. Interestingly, although none of the 7 kringle domains contained a canonical lysine-binding site, we found that recombinant HaRP-1 bound specifically to lysine-Sepharose. It is likely that the evolution of the HaRP-1 gene is coincident with the evolution of hedgehog apo(a), both of which occurred by duplication of the plasminogen kringle III motif. The function of HaRP-1 remains unclear at present, but may constititute a member of the family of apo(a) proteins that functions in the regulation of lysine-dependent proteolysis.
Belczewski
Andrea R
AR
Rm. A208 Botterell Hall, Department of Biochemistry, Queen's University, Kingston, Ont., Canada K7L 3N6.
Laplaud
P Michel
PM
Chapman
M John
MJ
Marcovina
Santica M
SM
Koschinsky
Marlys L
ML
D000595:Amino Acid Sequence; D000818:Animals; D001053:Apolipoproteins / Q000097:blood / Q000235:genetics*; D001483:Base Sequence; D015152:Blotting, Northern; D015153:Blotting, Western; D002460:Cell Line; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D015870:Gene Expression; D006364:Hedgehogs / Q000235:genetics*; D006801:Humans; D008099:Liver / Q000378:metabolism; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
D001053:Apolipoproteins; D018076:DNA, Complementary; D012333:RNA, Messenger; D011994:Recombinant Proteins