Biomaterial Database

A novel phospholipase A2 inhibitor with leucine-rich repeats from the blood plasma of Agkistrodon blomhoffii siniticus. Sequence homologies with human leucine-rich alpha2-glycoprotein. 1998

K Okumura, and N Ohkura, and S Inoue, and K Ikeda, and K Hayashi

Department of Biochemistry, Osaka University of Pharmaceutical Sciences, Nasahara, Takatsuki, Osaka 569-1094, Japan.

The phospholipase A2 (PLA2) inhibitor PLIbeta, purified from the blood plasma of Chinese mamushi snake (Agkistrodon blomhoffii siniticus), is a 160-kDa trimer with three 50-kDa subunits; and it inhibits specifically the enzymatic activity of the basic PLA2 from its own venom (Ohkura, N., Okuhara, H., Inoue, S., Ikeda, K., and Hayashi, K. (1997) Biochem. J. 325, 527-531). In the present study, the 50-kDa subunit was found to be glycosylated with N-linked carbohydrate, and enzymatic deglycosylation decreased the molecular mass of the 50-kDa subunit to 39-kDa. One 160-kDa trimer of PLIbeta was found to form a stable complex with three basic PLA2 molecules, indicating that one basic PLA2 molecule would bind stoichiometrically to one subunit of PLIbeta. A cDNA encoding PLIbeta was isolated from a Chinese mamushi liver cDNA library by use of a probe prepared by a polymerase chain reaction on the basis of the partially determined amino acid sequence of the subunit. The cDNA contained an open reading frame encoding a 23-residue signal sequence followed by a 308-residue protein, which contained the sequences of all the peptides derived by lysyl endopeptidase digestion of the subunit. The molecular mass of the mature protein was calculated to be 34,594 Da, and the deduced amino acid sequence contained four potential N-glycosylation sites. The sequence of PLIbeta showed no significant homology with that of the known PLA2 inhibitors. But, interestingly, it exhibited 33% identity with that of human leucine-rich alpha2-glycoprotein, a serum protein of unknown function. The most striking feature of the sequence is that it contained nine leucine-rich repeats (LRRs), each of 24 amino acid residues and thus encompassing over two-thirds of the molecule. LRRs in PLIbeta might be responsible for the specific binding to basic PLA2, since LRRs are considered as the motifs involved in protein-protein interactions.

UI	MeSH Term	Description	Entries
D007930	Leucine	An essential branched-chain amino acid important for hemoglobin formation.	L-Leucine,Leucine, L-Isomer,L-Isomer Leucine,Leucine, L Isomer
D008969	Molecular Sequence Data	Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.	Sequence Data, Molecular,Molecular Sequencing Data,Data, Molecular Sequence,Data, Molecular Sequencing,Sequencing Data, Molecular
D010741	Phospholipases A	Phospholipases that hydrolyze one of the acyl groups of phosphoglycerides or glycerophosphatidates.
D011485	Protein Binding	The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.	Plasma Protein Binding Capacity,Binding, Protein
D011487	Protein Conformation	The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).	Conformation, Protein,Conformations, Protein,Protein Conformations
D012091	Repetitive Sequences, Nucleic Acid	Sequences of DNA or RNA that occur in multiple copies. There are several types: INTERSPERSED REPETITIVE SEQUENCES are copies of transposable elements (DNA TRANSPOSABLE ELEMENTS or RETROELEMENTS) dispersed throughout the genome. TERMINAL REPEAT SEQUENCES flank both ends of another sequence, for example, the long terminal repeats (LTRs) on RETROVIRUSES. Variations may be direct repeats, those occurring in the same direction, or inverted repeats, those opposite to each other in direction. TANDEM REPEAT SEQUENCES are copies which lie adjacent to each other, direct or inverted (INVERTED REPEAT SEQUENCES).	DNA Repetitious Region,Direct Repeat,Genes, Selfish,Nucleic Acid Repetitive Sequences,Repetitive Region,Selfish DNA,Selfish Genes,DNA, Selfish,Repetitious Region, DNA,Repetitive Sequence,DNA Repetitious Regions,DNAs, Selfish,Direct Repeats,Gene, Selfish,Repeat, Direct,Repeats, Direct,Repetitious Regions, DNA,Repetitive Regions,Repetitive Sequences,Selfish DNAs,Selfish Gene
D001798	Blood Proteins	Proteins that are present in blood serum, including SERUM ALBUMIN; BLOOD COAGULATION FACTORS; and many other types of proteins.	Blood Protein,Plasma Protein,Plasma Proteins,Serum Protein,Serum Proteins,Protein, Blood,Protein, Plasma,Protein, Serum,Proteins, Blood,Proteins, Plasma,Proteins, Serum
D003001	Cloning, Molecular	The insertion of recombinant DNA molecules from prokaryotic and/or eukaryotic sources into a replicating vehicle, such as a plasmid or virus vector, and the introduction of the resultant hybrid molecules into recipient cells without altering the viability of those cells.	Molecular Cloning
D004791	Enzyme Inhibitors	Compounds or agents that combine with an enzyme in such a manner as to prevent the normal substrate-enzyme combination and the catalytic reaction.	Enzyme Inhibitor,Inhibitor, Enzyme,Inhibitors, Enzyme
D006023	Glycoproteins	Conjugated protein-carbohydrate compounds including MUCINS; mucoid, and AMYLOID glycoproteins.	C-Glycosylated Proteins,Glycosylated Protein,Glycosylated Proteins,N-Glycosylated Proteins,O-Glycosylated Proteins,Glycoprotein,Neoglycoproteins,Protein, Glycosylated,Proteins, C-Glycosylated,Proteins, Glycosylated,Proteins, N-Glycosylated,Proteins, O-Glycosylated