CD59a (Protectin)

Protectin, a complement regulatory protein, also known as CD59, or MIRL (membrane inhibitor of reactive lysis) is a small protein that inhibits the complement membrane attack complex by binding C5b678 and preventing C9 from binding and polymerizing. The amino-terminal 25 amino acids represented a typical signal peptide sequence and the carboxy-terminal hydrophobic amino acids were characteristic for phosphatidylinositol-anchored proteins.It was found that the CD59/Protectin antigen is a small protein sometimes associated with larger components (45 and 80 kD) in urine. CD59/Protectin antigen was released from the surface of transfected COS cells by phosphatidylinositol-specific phospholipase C, demonstrating that it is attached to the cell membrane by means of a glycolipid anchor; it is therefore likely to be absent from the surface of affected erythrocytes in the disease paroxysmal nocturnal hemoglobinuria.

CD59a (Protectin) Related Areas

Immunology>>Innate Immunity>>Complement System>> CD59a

Immunology>>Cluster of Differentiation>>Monocyte/Macrophage CD Antigen>>Macrophage Markers>> CD59a

CD59a (Protectin) Alternative Names

RP24-297H17.1, AA987121, Cd59, protectin[Mus musculus]

Summaries for CD59a (Protectin)

Wikipedia summary for CD59a (Protectin):

Protectin, a complement regulatory protein, also known as CD59, or MIRL (membrane inhibitor of reactive lysis) is a human gene and protein.
CD59 inhibits the complement membrane attack complex by binding C5b678 and preventing C9 from binding and polymerizing.[2] It is present on "self" cells to prevent complement from damaging them. CD59, along with CD55 are not present in the condition paroxysmal nocturnal hemoglobinuria. Viruses such as HIV, human cytomegalovirus and vaccinia incorporate host cell CD59 into their own viral envelope to prevent lysis by complement.

Human CD59a (Protectin) Protein General Information

 

• Protein names: CD59 glycoprotein
  CD_antigen=CD59
  
• Sequence length: 128 AA.
• Domain: Signal
• Sequence similarities: Contains 1 UPAR/Ly6 domain.
• Post-translational modification: N- and O-glycosylated. The N-glycosylation mainly consists of a family of biantennary complex-type structures with and without lactosamine extensions and outer arm fucose residues. Also significant amounts of triantennary complexes (22%). Variable sialylation also present in the Asn-43 oligosaccharide. The predominant O-glycans are mono-sialylated forms of the disaccharide, Gal-beta-1,3GalNAc, and their sites of attachment are probably on Thr-76 and Thr-77. The GPI-anchor of soluble urinary CD59 has no inositol-associated phospholipid, but is composed of seven different GPI-anchor variants of one or more monosaccharide units. Major variants contain sialic acid, mannose and glucosamine Sialic acid linked to an N-acetylhexosamine-galactose arm is present in two variants.
  Glycated. Glycation is found in diabetic subjects, but only at minimal levels in nondiabetic subjects. Glycated CD59 lacks MAC-inhibitory function and confers to vascular complications of diabetes.
• Subunit structure: Interacts with T-cell surface antigen CD2.
• Subcellular location: Cell membrane; Lipid-anchor › GPI-anchor. Secreted. Note: Soluble form found in a number of tissues.
• Involvement in disease: Defects in CD59 are the cause of CD59 deficiency (CD59D)

General information above from UniProt

Function for CD59a (Protectin) Protein

UniProtKB:

CD59a is potent inhibitor of the complement membrane attack complex (MAC) action. CD59a acts by binding to the C8 and/or C9 complements of the assembling MAC, thereby preventing incorporation of the multiple copies of C9 required for complete formation of the osmolytic pore. This inhibitor appears to be species-specific. CD59a is involved in signal transduction for T-cell activation complexed to a protein tyrosine kinase. The soluble form from urine retains its specific complement binding activity, but exhibits greatly reduced ability to inhibit MAC assembly on cell membranes.

Genatlas:

• CD59a is homologous restriction factor (18 kD) binding through C8G to the membrane attack complex of complement as a membrane inhibitor of cell lysis
• CD59a functions as a co-receptor in natural killer cell activation
• CD59a inhibits assembly of the lytic membrane attack complex of complement by incorporation into the forming complex

Homology for human CD59a (Protectin)

• ortholog to murine lymphocyte antigen Ly-6L

Phenotype Information for CD59a (Protectin)

• Gene/Locus: CD59, MIC11
• Phenotype: CD59 deficiency

Phenotype Information for CD59a (Protectin) from OMIM (Online Mendelian Inheritance in Man)