Abstract
Membrane cofactor protein (MCP; CD46) regulates the complement cascade by inhibiting C3b and C4b deposited on self tissue. This function resides in the complement control protein repeats (CCPs), with CCPs 2-4 essential for regulation. MCP is expressed on the inner acrosomal membrane of human sperm, and Abs to CCP1 inhibit sperm-egg interactions. In somatic tissues, New World monkeys express an alternatively spliced form of MCP lacking CCP1. Although retaining complement-regulatory activity, this form is postulated to render these species less susceptible to strains of the measles virus whose hemagglutinin requires CCP1 and CCP2 for attachment. Using PCR, sequencing, Western blotting, and immunohistochemistry, we characterized MCP expression in the testes and sperm of two New World monkeys. In these species, sperm express MCP bearing CCP1. The germ cell-specific expression pattern of this domain strongly suggests an evolutionarily conserved role for MCP in fertilization.
Publication types
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Comparative Study
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Acrosome Reaction / immunology*
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Alternative Splicing / immunology*
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Animals
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Antigens, CD / biosynthesis
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Antigens, CD / genetics
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Antigens, CD / isolation & purification
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Antigens, CD / physiology*
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Callithrix
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Carbohydrate Conformation
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Electrophoresis, Polyacrylamide Gel
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Glycosylation
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Humans
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Intracellular Membranes / chemistry
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Intracellular Membranes / metabolism
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Male
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Measles / genetics
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Measles / immunology
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Measles / physiopathology*
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Measles / prevention & control*
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Membrane Cofactor Protein
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Membrane Glycoproteins / analysis
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Membrane Glycoproteins / biosynthesis
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Membrane Glycoproteins / genetics
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Membrane Glycoproteins / isolation & purification
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Membrane Glycoproteins / physiology*
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Molecular Sequence Data
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Organ Specificity / genetics
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Organ Specificity / immunology
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RNA, Messenger / metabolism
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Receptors, Virus / biosynthesis
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Receptors, Virus / genetics
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Receptors, Virus / isolation & purification
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Receptors, Virus / physiology*
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Repetitive Sequences, Amino Acid
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Saimiri
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Spermatozoa / chemistry
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Spermatozoa / metabolism
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Testis / chemistry
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Testis / metabolism
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Viral Proteins / analysis
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Viral Proteins / genetics
Substances
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Antigens, CD
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CD46 protein, human
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Membrane Cofactor Protein
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Membrane Glycoproteins
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RNA, Messenger
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Receptors, Virus
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Viral Proteins
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herpesvirus saimiri protein, Saimiriine herpesvirus 2
Associated data
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GENBANK/AY157981
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GENBANK/AY157982
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GENBANK/AY157983
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GENBANK/AY157984
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GENBANK/AY157985