Biomaterial Database

Third component of trout complement. cDNA cloning and conservation of functional sites. 1993

J D Lambris, and Z Lao, and J Pang, and J Alsenz

Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadephia 19104.

Of the 30 distinct complement proteins recognized to date, C3 is probably the most versatile and multifunctional molecule known, interacting with at least 20 different proteins. It plays a critical role in both pathways of complement activation and participates in phagocytic and immunoregulatory processes. Structural and functional analysis of C3 from different species, in addition to phylogenetic information, provides insights into the structural elements mediating the various functions. This study describes the cDNA cloning of one of two isoforms of the third complement component, C3-1, of rainbow trout (Salmo gairdneri) and the analysis of its functional sites. By screening a trout liver lambda gt11 library with anti-trout C3 chain-specific antibodies and polymerase chain reaction we have determined the cDNA sequence of trout C3-1. The obtained sequence is in complete agreement with the protein sequence of several tryptic peptides, corresponding to different regions of trout C3-1. C3-1 consists of 1640 amino acids with a calculated molecular mass of 181,497 Da. The sequence contains two potential N-glycosylation sites, one on each chain of C3. The deduced protein sequence showed 44.1, 43.3, 44.2, 44.9, 43.1, 43.8, 45.9, 29.9, and 33.1% amino acid identities to human, mouse rat, guinea pig, rabbit, cobra, frog, hagfish, and lamprey C3, whereas the identities to human C4, C5, and alpha 2M are 30.4, 28, and 22.9%, respectively. The trout C3 amino acid sequence shows clusters of high and low similarity to C3 from other species. In the regions of high similarity belong the C3 domains that contain the thiolester site and the properdin binding sites, whereas the regions that correspond to regions of human C3 where CR1 and CR2 bind show low amino acid sequence similarity. The deduced amino acid sequence shows that the C3 convertase cleavage site (Arg-Ser) is conserved in trout C3, whereas the factor I cleavage sites are Arg-Ala and Arg-Thr instead of Arg-Ser, which is found in the C3 of other species. Protein sequencing of the trout C3 fragments fixed on zymosan during complement activation confirmed the cleavage of trout C3 by trout C3 convertase and factor I at Arg-Ser and Arg-Thr, respectively.

UI	MeSH Term	Description	Entries
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
D003176	Complement C3	A glycoprotein that is central in both the classical and the alternative pathway of COMPLEMENT ACTIVATION. C3 can be cleaved into COMPLEMENT C3A and COMPLEMENT C3B, spontaneously at low level or by C3 CONVERTASE at high level. The smaller fragment C3a is an ANAPHYLATOXIN and mediator of local inflammatory process. The larger fragment C3b binds with C3 convertase to form C5 convertase.	C3 Complement,C3 Precursor,Complement 3,Complement C3 Precursor,Complement Component 3,Precursor-Complement 3,Pro-C3,Pro-Complement 3,C3 Precursor, Complement,C3, Complement,Complement, C3,Component 3, Complement,Precursor Complement 3,Precursor, C3,Precursor, Complement C3,Pro C3,Pro Complement 3
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000595	Amino Acid Sequence	The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.	Protein Structure, Primary,Amino Acid Sequences,Sequence, Amino Acid,Sequences, Amino Acid,Primary Protein Structure,Primary Protein Structures,Protein Structures, Primary,Structure, Primary Protein,Structures, Primary Protein
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D001483	Base Sequence	The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.	DNA Sequence,Nucleotide Sequence,RNA Sequence,DNA Sequences,Base Sequences,Nucleotide Sequences,RNA Sequences,Sequence, Base,Sequence, DNA,Sequence, Nucleotide,Sequence, RNA,Sequences, Base,Sequences, DNA,Sequences, Nucleotide,Sequences, RNA
D014337	Trout	Various fish of the family SALMONIDAE, usually smaller than salmon. They are mostly restricted to cool clear freshwater. Some are anadromous. They are highly regarded for their handsome colors, rich well-flavored flesh, and gameness as an angling fish. The genera Salvelinus, Salmo, and ONCORHYNCHUS have been introduced virtually throughout the world.	Chars,Salvelinus,Char
D017124	Conserved Sequence	A sequence of amino acids in a polypeptide or of nucleotides in DNA or RNA that is similar across multiple species. A known set of conserved sequences is represented by a CONSENSUS SEQUENCE. AMINO ACID MOTIFS are often composed of conserved sequences.	Conserved Sequences,Sequence, Conserved,Sequences, Conserved
D017244	Complement Factor I	A plasma serine proteinase that cleaves the alpha-chains of C3b and C4b in the presence of the cofactors COMPLEMENT FACTOR H and C4-binding protein, respectively. It is a 66-kDa glycoprotein that converts C3b to inactivated C3b (iC3b) followed by the release of two fragments, C3c (150-kDa) and C3dg (41-kDa). It was formerly called KAF, C3bINF, or enzyme 3b inactivator.	C3b Inactivator,C3b-C4b Inactivator,C4b-C3b-INA,C4bC3bINA,Complement 3b-Complement 4b Inactivator,Complement C4b-C3b Inactivator,C3b C4b Inactivator,C4b C3b INA,C4b-C3b Inactivator, Complement,Complement 3b Complement 4b Inactivator,Complement C4b C3b Inactivator,Inactivator, C3b,Inactivator, C3b-C4b,Inactivator, Complement C4b-C3b
D050577	Complement C3-C5 Convertases	Serine proteases that cleave COMPLEMENT C3 into COMPLEMENT C3A and COMPLEMENT C3B, or cleave COMPLEMENT C5 into COMPLEMENT C5A and COMPLEMENT C5B. These include the different forms of C3/C5 convertases in the classical and the alternative pathways of COMPLEMENT ACTIVATION. Both cleavages take place at the C-terminal of an ARGININE residue.	C3 Convertase,C 3 Convertase,C3 Activator,C3-C5 Convertase,C5 Cleaving Enzyme,C5 Convertase,Complement 3 Convertase,Complement 5 Convertase,Complement C3 Convertases,Complement C5 Convertases,Activator, C3,C3 C5 Convertase,C3 Convertases, Complement,C3-C5 Convertases, Complement,C5 Convertases, Complement,Complement C3 C5 Convertases,Convertase, C 3,Convertase, C3,Convertase, C3-C5,Convertase, Complement 3,Convertases, Complement C3,Convertases, Complement C3-C5,Convertases, Complement C5