• gpL115
• leukocyte sialoglycoprotein
• leukosialin
• sialophorin

MAJOR LINKS FOR CD43  

• NCBI LocusLink Record: 6693
• Mendelian Inheritance in Man (OMIM): 182160
• SwissProt annotated protein record: P16150

CELLULAR FUNCTION OF CD43  

• CD43 appears to be an anti-adhesive ("barrier") molecule mediating (due to its extended rod-like shape and presence of large number of negative sialic acid residues) repulsion between leukocytes and other cells (Majunath N et al. 1993)
• Alternatively, under some circumstances, CD43 may act as an adhesion molecule possibly via its interaction with CD54 (Rosenstein et al. 1991) or (a speculation) with some lectin receptors
• Ligation of CD43 by specific mAbs may induce activation in T cells (Mentzer S J et al. 1987; Alvarado M et al. 1995) or monocytes (Nong Y-H et al. 1989) and apoptosis in hematopoietic progenitors (Bazil V et al. 1995)

DISEASE RELEVANCE OF CD43 AND FUNCTION OF CD43 IN INTACT ANIMAL  

• Abnormally low and abnormal CD43 expression was reported in T cells of patients with Wiskott-Aldrich syndrome, but this is only a secondary consequence of the primary defect in the gene responsible for this disorder

• Families in which CD43 is a member
  • CD43-->sialomucin-->Mucins

MOLECULAR STRUCTURE OF CD43  

• Single chain type I transmembrane molecule (385 amino acids) (Pallant A et al. 1989)
• 245 amino acid extracellular region consisting of 5 repeats of an 18 amino acid sequence rich in serine and threonine
• The extracellular region has an extended structure of approximately 45 nm in length (Cyster JG et al. 1991)

MOLECULAR MASS OF CD43  

POST-TRANSCRIPTIONAL MODIFICATION OF CD43  

• Splicing cannot occur (single-exon gene) (Shelley CS et al. 1990)

POST-TRANSLATIONAL MODIFICATION OF CD43  

• Extensive serine/threonine glycosylation of the entire extracellular region, single N-linked glycan in the membrane-proximal part
• Constitutive phosphorylation on serine residues in the intracellular region; the level of phosphorylation increases upon cell activation
• A soluble form of CD43 called galactoglycoprotein is present in blood plasma, which is apparently produced by proteolytic cleavage (shedding) of the extracellular region (Schmid K et al. 1992)

SUBSTRATES FOR CD43   - No information

ENZYMES WHICH MODIFY CD43  

LIGANDS FOR CD43 AND MOLECULES ASSOCIATED WITH CD43  

• Expressed, typically at high levels, on all leukocytes except most resting B lymphocytes. Expression on platelets is weak
• Different cell types express CD43 forms differing in the degree of sialylation of the O-linked oligosaccharide chains
• CD43 is rapidly lost from lymphocyte and neutrophil surface by proteolytic shedding after activation with various stimuli

• An important unresolved question is how CD43 signals under physiological conditions and what is the physiological trigger for this signaling

SELECTION OF OTHER CD43-SPECIFIC REFERENCE MAB  

REVIEWS

PRIMARY CITATIONS

1. Alvarado M,Klassen C,Cerny J,Horejsi V,Schmidt RE MEM-59 monoclonal antibody detects a CD43 epitope involved in lymphocyte activation. Eur J Immunol 1995 25:1051 PubMed

2. Bazil V,Brandt J,Tsukamoto A,Hoffman R Apoptosis of human hematopoietic progenitor cells induced by crosslinking of surface CD43, the major sialoglycoprotein of leukocytes. Blood 1995 86:502 PubMed

3. Cyster JG,Shotton DM,Williams AF The dimensions of the T lymphocyte glycoprotein leukosialin and identification of linear protein epitopes that can be modified by glycosylation. EMBO J 1991 10:893 PubMed

4. Kudo S,Fukuda M Tissue-specific transcriptional regulation of human leukosialin (CD43) gene is achieved by DNA methylation. J Biol Chem 1995 270:13298 PubMed

5. Manjunath N,Johnson RS,Staunton DE,Pasqualini R,Ardman B Targeted disruption of CD43 gene enhances T lymphocyte adhesion. J Immunol 1993 151:1528 PubMed

6. Mentzer SJ,Remold-O'Donnell E,Crimmins MA,Bierer BE,Rosen FS,Burakoff SJ Sialophorin, a surface sialoglycoprotein defective in the Wiskott- Aldrich syndrome, is involved in human T lymphocyte proliferation. J Exp Med 1987 165:1383 PubMed

7. Nong YH,Remold-O'Donnell E,LeBien TW,Remold HG A monoclonal antibody to sialophorin (CD43) induces homotypic adhesion and activation of human monocytes. J Exp Med 1989 170:259 PubMed

8. Pallant A,Eskenazi A,Mattei MG,Fournier RE,Carlsson SR,Fukuda M,Frelinger JG Characterization of cDNAs encoding human leukosialin and localization of the leukosialin gene to chromosome 16. Proc Natl Acad Sci U S A 1989 86:1328 PubMed

9. Rosenstein Y,Park JK,Hahn WC,Rosen FS,Bierer BE,Burakoff SJ CD43, a molecule defective in Wiskott-Aldrich syndrome, binds ICAM-1. Nature 1991 354:233 PubMed

10. Schmid K,Hediger MA,Brossmer R,Collins JH,Haupt H,Marti T,Offner GD,Schaller J,Takagaki K,Walsh MT,et al Amino acid sequence of human plasma galactoglycoprotein: identity with the extracellular region of CD43 (sialophorin). Proc Natl Acad Sci U S A 1992 89:663 PubMed

11. Shelley CS,Remold-O'Donnell E,Rosen FS,Whitehead AS Structure of the human sialophorin (CD43) gene. Identification of features atypical of genes encoding integral membrane proteins. Biochem J 1990 270:569 PubMed

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Portions copyright by Garland Press and by the International Workshops on Human Leukocyte Differentiation Antigens; used with permission

Modified 10/14/99   mpr@mail.nih.gov