LPA protease-domain sequence compatibility analysis
-
The P08519 protease-like domain retains the aligned His-Asp-Ser charge-relay residues.
"All three PLG charge-relay residues map without a gap to the same residue type in P08519: PLG H622/D665/S760 correspond to apo(a) H1861/D1904/S1990."
-
The plasminogen activation-site arginine is replaced by serine in P08519, providing sequence evidence for an activation-defective domain.
"At the homologous apo(a) protease-domain boundary, the sequence is S1819|I1820 and UniProt provides no cleavage annotation."
-
The sequence analysis does not itself prove absolute catalytic inactivity or negate curator-read experimental evidence.
"This sequence result cannot establish absolute inactivity. It neither reproduces nor refutes the older experimental report associated with UniProt's “serine proteinase activity” statement, and it cannot exclude noncanonical cleavage, context-dependent activity, or activity attributed to another component or contaminant in an Lp(a) preparation."
UniProtKB entry P08519 (APOA_HUMAN), cached in the gene folder
-
The reference record bounds the extensive KIV-2 copy-number polymorphism.
"Depending on the individual, the encoded protein contains 2-43 copies"
-
P08519 represents a specific 15-copy reference allele rather than a universal apo(a) product length.
"here contains 15 copies of the kringle-type repeats."
-
UniProt attributes serine-proteinase/autoproteolysis to the single older catalytic report.
"has serine proteinase activity and is able of autoproteolysis. Inhibits"
Gene Ontology annotation through association of InterPro records with GO terms
Electronic Gene Ontology annotations created by ARBA machine learning models
The human plasma proteome: a nonredundant list developed by combination of four separate sources.
-
LPA was included in a nonredundant catalogue of proteins reported in human plasma or serum.
"We have merged four different views of the human plasma proteome, based on different methodologies, into a single nonredundant list of 1175 distinct gene products."
Lipoprotein(a) binds to fibronectin and has serine proteinase activity capable of cleaving it.
-
Purified Lp(a)/apo(a) bound immobilized fibronectin, with binding localized to fibronectin's C-terminal heparin-binding domain.
"The binding of Lp(a) was localized to the C-terminal heparin-binding domain of fibronectin."
-
The study attributed fibronectin fragmentation and synthetic-substrate cleavage to a serine-proteinase-type activity of apo(a).
"The proteolytic activity of Lp(a) was localized to apo(a) and experiments with inhibitors indicated that the proteolytic activity was of serine proteinase-type."
Activation of transforming growth factor-beta is inhibited in transgenic apolipoprotein(a) mice.
-
Human apo(a) expression in transgenic mice inhibited plasminogen activation and consequently reduced TGF-beta activation.
"We show here that the activation of TGF-beta is inhibited in the aortic wall and serum of mice expressing apolipoprotein(a), as a consequence of apolipoprotein(a) inhibition of plasminogen activation."
Novel interaction of apolipoprotein(a) with beta-2 glycoprotein I mediated by the kringle IV domain.
-
A KIV-2 yeast two-hybrid screen identified beta-2-glycoprotein I, and coimmunoprecipitation confirmed apo(a)/Lp(a)-APOH interaction in plasma and cell supernatants.
"Coimmunoprecipitation experiments confirmed that beta-2 glycoprotein I and apo(a)/Lp(a) interact in human plasma and in cell culture supernatants of COS-1 cells, which ectopically expressed apo(a)."
Partial amino acid sequence of apolipoprotein(a) shows that it is homologous to plasminogen.
-
Apo(a) has a serine at the position homologous to the plasminogen activation-site arginine and was inactive in a plasmin-specific assay.
"Plasminogen is activated by the cleavage of a specific arginine residue by urokinase and tissue plasminogen activator; however, the corresponding site in apo(a) is a serine that would not be cleaved by tissue plasminogen activator or urokinase."
-
The authors interpreted the biochemical and sequence results as an inactive protease domain.
"Using a plasmin-specific assay, no proteolytic activity could be demonstrated for lipoprotein(a) particles."
Analysis of the proteolytic activity of a recombinant form of apolipoprotein(a).
-
Restoring an arginine at the activation junction permitted tPA cleavage but did not produce an active protease.
"However, tPA cleavage did not result in an active protease as both wildtype r-apo(a) and the mutant, either free or incorporated into r-Lp(a) particles, were uniformly inactive against a variety of chromogenic serine protease tripeptide substrates."
-
Additional protease-domain substitutions, not only the Arg-to-Ser activation-site change, were inferred to disable apo(a) catalysis.
"The results of this study suggest that one or more of the substitutions present in the protease domain of apo(a), in addition to the Arg-->Ser substitution, render apo(a) proteolytically inactive."
Identification of the cysteine residue in apolipoprotein(a) that mediates extracellular coupling with apolipoprotein B-100.
-
Recombinant apo(a) formed covalent extracellular complexes with apoB-100-containing lipoprotein particles.
"However, covalent r-Lp(a) complexes were observed in the transfected cell supernatants."
-
Site-directed mutagenesis identified apo(a) Cys4057 as participating in the disulfide linkage to apoB-100.
"Using site-directed mutagenesis, we demonstrated that Cys4057 in apo(a) is involved in disulfide linkage with apoB-100 in Lp(a) particles."
Cys4057 of apolipoprotein(a) is essential for lipoprotein(a) assembly.
-
Substitution of apo(a) Cys4057 prevented formation of lipoprotein-associated apo(a) in HepG2 supernatants.
"The same analysis performed with supernatants of cells transfected with plasmids mutated in codon 4057 revealed free apolipoprotein(a) glycoprotein without detectable amounts of lipoprotein-associated apolipoprotein(a)."
Comparative analyses of the lysine binding site properties of apolipoprotein(a) kringle IV types 7 and 10.
-
Recombinant KIV-7 directly bound lysine analogues, but more weakly than the canonical KIV-10 lysine-binding site.
"Equilibrium binding analyses of the KIV(7) LBS using intrinsic fluorescence revealed an affinity for L-lysine and its analogues approximately 10-fold weaker (K(D) = 230 +/- 42 microM for epsilon-aminocaproic acid) than that of KIV(10) (K(D) = 33 +/- 4 microM for epsilon-aminocaproic acid)."
A single point mutation (Trp72-->Arg) in human apo(a) kringle 4-37 associated with a lysine binding defect in Lp(a).
-
A naturally occurring Trp-to-Arg apo(a) kringle variant abolished Lp(a) binding to lysine-Sepharose.
"For the first time we now report the occurrence of a human Lp(a) that has a mutant form of apo(a) where Arg has replaced Trp in position 72 of kringle 4-37 and is unable to bind to lysine Sepharose."
Tissue-type plasminogen activator binds to and is inhibited by surface-bound lipoprotein(a) and low-density lipoprotein.
-
Surface-bound Lp(a), but not Lp(a) in solution, bound tPA and reduced its catalytic efficiency toward plasminogen.
"We now report that t-PA binds reversibly and saturably to surface-bound Lp(a) and to low-density lipoprotein (LDL) and that as a result of this binding activation of plasminogen by t-PA is inhibited."
Inhibition of plasminogen activation by lipoprotein(a): critical domains in apolipoprotein(a) and mechanism of inhibition on fibrin and degraded fibrin surfaces.
-
Lp(a) and recombinant apo(a) inhibited tPA-mediated plasminogen activation on fibrin cofactors.
"Human Lp(a) and a physiologically relevant, 17-kringle recombinant apo(a) species exhibited strong inhibition with both cofactors."
-
Antifibrinolytic inhibition persisted without the protease domain and depended strongly on kringle lysine-binding determinants.
"A variant lacking the protease domain also exhibited strong inhibition, indicating that the apo(a)-plasminogen binding interaction mediated by the apo(a) protease domain does not ultimately inhibit plasminogen activation."
The number of kringle IV repeats 3-10 is invariable in the human apo(a) gene.
-
Across alleles spanning 11-49 total kringles, KIV types 3-10 remained single-copy while KIV-2 accounted for size variation.
"Our analysis demonstrates that the number of kringles IV 3-10 is invariable in the human apo(a) gene, suggesting that the 3'domain of Apo(a) is functionally important."
cDNA sequence of human apolipoprotein(a) is homologous to plasminogen.
-
The cloned apo(a) product contains repeated plasminogen-like kringles and a serine-protease-homologous domain.
"It contains a serine protease domain and two types of plasminogen-like kringle domains, one of which is present in 37 copies."
apolipoprotein(a) + LDL => Lp(a)