Apolipoprotein L, a new human high density lipoprotein apolipoprotein expressed by the pancreas. Identification, cloning, characterization, and plasma distribution of apolipoprotein L.
In this study, we have identified and characterized a new protein present in human high density lipoprotein that we have designated apolipoprotein L. Using a combination of liquid-phase isoelectrophoresis and high resolution two-dimensional gel electrophoresis, apolipoprotein L was identified and partially sequenced from immunoisolated high density lipoprotein (Lp(A-I)). Expression was only detected in the pancreas. The cDNA sequence encoding the full-length protein was cloned using reverse transcription-polymerase chain reaction. The deduced amino acid sequence contains 383 residues, including a typical signal peptide of 12 amino acids. No significant homology was found with known sequences. The plasma protein is a single chain polypeptide with an apparent molecular mass of 42 kDa. Antibodies raised against this protein detected a truncated form with a molecular mass of 39 kDa. Both forms were predominantly associated with immunoaffinity-isolated apoA-I-containing lipoproteins and detected mainly in the density range 1.123 < d < 1.21 g/ml. Free apoL was not detected in plasma. Anti-apoL immunoaffinity chromatography was used to purify apoL-containing lipoproteins (Lp(L)) directly from plasma. Nondenaturing gel electrophoresis of Lp(L) showed two major molecular species with apparent diameters of 12.2-17 and 10.4-12.2 nm. Moreover, Lp(L) exhibited both pre-beta and alpha electromobility. Apolipoproteins A-I, A-II, A-IV, and C-III were also detected in the apoL-containing lipoprotein particles.
Duchateau
P N
PN
Cardiovascular Research Institute, University of California, San Francisco, California 94143-0130, USA.
Pullinger
C R
CR
Orellana
R E
RE
Kunitake
S T
ST
Naya-Vigne
J
J
O'Connor
P M
PM
Malloy
M J
MJ
Kane
J P
JP
D000595:Amino Acid Sequence; D000075944:Apolipoprotein L1; D001053:Apolipoproteins / Q000096:biosynthesis* / Q000235:genetics / Q000302:isolation & purification; D001483:Base Sequence; D015152:Blotting, Northern; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000032:analysis; D005260:Female; D006801:Humans; D017270:Lipoprotein(a) / Q000031:analogs & derivatives / Q000737:chemistry; D008075:Lipoproteins, HDL / Q000096:biosynthesis* / Q000235:genetics / Q000302:isolation & purification; D008297:Male; D008969:Molecular Sequence Data; D010179:Pancreas / Q000378:metabolism*; D017433:Protein Structure, Secondary
C108666:APOL1 protein, human; D000075944:Apolipoprotein L1; D001053:Apolipoproteins; D018076:DNA, Complementary; D017270:Lipoprotein(a); D008075:Lipoproteins, HDL; C078260:lipoprotein A-I