Fish apolipoprotein-A-I has heparin binding activity: implication for nerve regeneration.
This study provides evidence that apolipoprotein-A-I (apo-A-I), derived from fish plasma and nerve, has heparin binding activity. We have shown previously that injury in a regenerative CNS, such as that of fish optic nerves, leads to increased levels of apo-A-I in media conditioned by these nerves, as compared with media conditioned by noninjured nerves. In the present study, we have purified and characterized apo-A-I from both fish plasma and optic nerves. Sequence analysis of the 15 N-terminal amino acids revealed that at least 14 amino acids are identical in these two purified apo-A-I samples. The purified apo-A-I derived from both fish plasma and optic nerves binds to heparin. Binding measurements using [3H]heparin followed by Scatchard analysis revealed that apo-A-I binds to heparin with relatively low affinity (KD = 2.8 x 10(-6) M). Results are discussed with respect to the possibility that accumulation of apo-A-I in the extracellular matrix of fish optic nerves is made possible via heparin binding, like that to apolipoprotein-E in mammals.
Harel
A
A
Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel.
Fainaru
M
M
Rubinstein
M
M
Tal
N
N
Schwartz
M
M
D000595:Amino Acid Sequence; D000818:Animals; D016632:Apolipoprotein A-I; D001054:Apolipoproteins A / Q000097:blood / Q000302:isolation & purification / Q000378:metabolism*; D002347:Carps; D002850:Chromatography, Gel; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D006493:Heparin / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008075:Lipoproteins, HDL / Q000378:metabolism*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009416:Nerve Regeneration; D009900:Optic Nerve / Q000378:metabolism / Q000502:physiology*; D011485:Protein Binding; D012689:Sequence Homology, Nucleic Acid
D016632:Apolipoprotein A-I; D001054:Apolipoproteins A; D008075:Lipoproteins, HDL; D006493:Heparin