CD55.

[pic 1]

CD55

Also named DAF, CD55 is a single chain, glycosylphosphatidylinositol (GPI)-anchored, type I

cell surface protein. It inhibits formation of the C3 convertases through binding to C3b and C4b.

It also binds the alternate pathway convertase C3bBb, the classical pathway convertase and

C4b2a to accelerate their decay. Inasmuch as it works optimally with human complement, while

not with complement of other species, it is commonly said to show homologous restriction [16].

The function of CD55 is to provide a protective barrier threshold against complement activation

and deposition on the plasma membranes of normal autologous cells, especially by the

classical pathway, by limiting the formation and reducing the half-life of the C3 convertases. It is

widely expressed on cells throughout the body but its density of expression differs from one cell

type to other. Its weak expression on NK cells seems to be associated with reduced efficiency

of target cell lysis [17]. The molecular mass of CD55 on red blood cells is about 5kDa less than

Ruiz-Argüelles A and Llorente L, Page 4

on nucleated cells as a result of differential glycosylation. Genetic defects in the CD55 gene or

GPI-anchor attachment cause reduction or loss of CD55 (and CD59) on erythrocytes, and thus

the signs and symptoms of a rather uncommon disease called paroxysmal nocturnal

hemoglobinuria (PNH) [18,19].

CD55

Also named DAF, CD55 is a single chain, glycosylphosphatidylinositol (GPI)-anchored, type I

cell surface protein. It inhibits formation of the C3 convertases through binding to C3b and C4b.

It also binds the alternate pathway convertase C3bBb, the classical pathway convertase and

C4b2a to accelerate their decay. Inasmuch as it works optimally with human complement, while

not with complement of other species, it is commonly said to show homologous restriction [16].

The function of CD55 is to provide a protective barrier threshold against complement activation

and deposition on the plasma membranes of normal autologous cells, especially by the

classical pathway, by limiting the formation and reducing the half-life of the C3 convertases. It is

widely expressed on cells throughout the body but its density of expression differs from one cell

type to other. Its weak expression on NK cells seems to be associated with reduced efficiency

of target cell lysis [17]. The molecular mass of CD55 on red blood cells is about 5kDa less than

Ruiz-Argüelles A and Llorente L, Page 4

on nucleated cells as a result of differential glycosylation. Genetic defects in the CD55 gene or

GPI-anchor attachment cause reduction or loss of CD55 (and CD59) on erythrocytes, and thus

the signs and symptoms of a rather uncommon disease called paroxysmal nocturnal

hemoglobinuria (PNH) [18,19].

CD55

Also named DAF, CD55 is a single chain, glycosylphosphatidylinositol (GPI)-anchored, type I

cell surface protein. It inhibits formation of the C3 convertases through binding to C3b and C4b.

It also binds the alternate pathway convertase C3bBb, the classical pathway convertase and

C4b2a to accelerate their decay. Inasmuch as it works optimally with human complement, while

not with complement of other species, it is commonly said to show homologous restriction [16].

The function of CD55 is to provide a protective barrier threshold against complement activation

and deposition on the plasma membranes of normal autologous cells, especially by the

classical pathway, by limiting the formation and reducing the half-life of the C3 convertases. It is

widely expressed on cells throughout the body but its density of expression differs from one cell

type to other. Its weak expression on NK cells seems to be associated with reduced efficiency

of target cell lysis [17]. The molecular mass of CD55 on red blood cells is about 5kDa less than

Ruiz-Argüelles A and Llorente L, Page 4

on nucleated cells as a result of differential glycosylation. Genetic defects in the CD55 gene or

GPI-anchor attachment cause reduction or loss of CD55 (and CD59) on erythrocytes, and thus

the signs and symptoms of a rather uncommon disease called paroxysmal nocturnal

hemoglobinuria (PNH) [18,19].

CD55

Also named DAF, CD55 is a single chain, glycosylphosphatidylinositol (GPI)-anchored, type I

cell surface protein. It inhibits formation of the C3 convertases through binding to C3b and C4b.

It also binds the alternate pathway convertase C3bBb, the classical pathway convertase and

C4b2a to accelerate their decay. Inasmuch as it works optimally with human complement, while

not with complement of other species, it is commonly said to show homologous restriction [16].

The function of CD55 is to provide a protective barrier threshold against complement activation

and deposition on the plasma membranes of normal autologous cells, especially by the

classical pathway, by limiting the formation and reducing the half-life of the C3 convertases. It is

widely expressed on cells throughout the body but its density of expression differs from one cell

type to other. Its weak expression on NK cells seems to be associated with reduced efficiency

of target cell lysis [17]. The molecular mass of CD55 on red blood cells is about 5kDa less than

Ruiz-Argüelles A and Llorente L, Page 4

on nucleated cells as a result of differential glycosylation. Genetic defects in the CD55 gene or

GPI-anchor attachment cause reduction or loss of CD55 (and CD59) on erythrocytes, and thus

the signs and symptoms of a rather uncommon disease called paroxysmal nocturnal

hemoglobinuria (PNH) [18,19].

CD55

Also named DAF, CD55 is a single chain, glycosylphosphatidylinositol (GPI)-anchored, type I

cell surface protein. It inhibits formation of the C3 convertases through binding to C3b and C4b.

It also binds the alternate pathway convertase C3bBb, the classical pathway convertase and

C4b2a to accelerate their decay. Inasmuch as it works optimally with human complement, while

not with complement of other species, it is commonly said to show homologous restriction [16].

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