Human factor H-related protein 5 (FHR-5). A new complement-associated protein.
A novel human plasma protein has been identified as a universal component of complement deposits, when complement is detected immunohistochemically in vivo. The protein is homologous to complement factor H and related proteins and has been designated factor H-related protein 5 (FHR-5). FHR-5 was identified by a monoclonal antibody raised using pathologic human glomerular preparations as the immunogen. FHR-5 was purified by affinity chromatography from complement-lysed erythrocytes, and the peptide sequence was obtained. The cDNA was cloned from a human liver library, and FHR-5 was deduced to be a protein containing 551 amino acids organized into nine short consensus repeat motifs. The short consensus repeats of FHR-5 show homology to Factor H and to other Factor H-related proteins, with some unique features demonstrated. Recombinant FHR-5, expressed in insect cells, was shown to bind C3b in vitro. The strong association of FHR-5 with tissue complement deposits in vivo suggests that this additional member of the Factor H family of proteins has a function in complement regulation.
McRae
J L
JL
Department of Nephrology, St. Vincent's Hospital, Fitzroy 3065, Australia. mcraej@svhm.org.au
Cowan
P J
PJ
Power
D A
DA
Mitchelhill
K I
KI
Kemp
B E
BE
Morgan
B P
BP
Murphy
B F
BF
D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D001053:Apolipoproteins / Q000032:analysis; D001798:Blood Proteins / Q000032:analysis* / Q000737:chemistry / Q000235:genetics; D015152:Blotting, Northern; D015153:Blotting, Western; D003001:Cloning, Molecular; D017242:Complement Factor H / Q000378:metabolism; D008969:Molecular Sequence Data; D011817:Rabbits; D011994:Recombinant Proteins / Q000032:analysis
D000911:Antibodies, Monoclonal; D001053:Apolipoproteins; D001798:Blood Proteins; C493495:CFH protein, human; C105092:CFHR4 protein, human; D011994:Recombinant Proteins; D017242:Complement Factor H