The carbohydrate-recognition domain of E-selectin is sufficient for ligand binding under both static and flow conditions.
Selectins are a family of adhesion molecules with a well-defined domain structure comprised of a lectin or carbohydrate-recognition domain (CRD), an epidermal growth factor (EGF)-like motif, and a variable number of consensus repeats (CRs). While it is clear from various lines of evidence that the CRD plays a pivotal role in selectin-ligand interactions, little is known about the role of the non-lectin selectin domains. We expressed a series of soluble chimeric proteins with various domains switched between E- and L-selectin and measured binding of the resulting chimeras to sialyl Lewis(a) and sulfatide, two carbohydrate structures which are specific for the E- and L-CRDs, respectively. Both CRDs bind to their respective ligands with the same affinity regardless of the origin of the other domains they are attached to. The domain-switched chimeras were assayed for their ability to support static binding and rolling of various cell lines which bind specifically to E-selectin. In these assays, the E-CRD was indispensable for both static binding and rolling under physiological flow conditions. The E-CRD alone, when substituted into L-selectin, supported rolling without the requirement for additional ligand-recognition elements. We conclude that the EGF domain or the CRs of E- and L-selectin have no influence on the CRD's specificity to carbohydrates. Furthermore, at least in the case of E-selectin, they do not contribute to the specificity of binding to cell surface ligands.
Kolbinger
F
F
Ciba Central Research, Basel, Switzerland.
Patton
J T
JT
Geisenhoff
G
G
Aenis
A
A
Li
X
X
Katopodis
A G
AG
D000818:Animals; D001665:Binding Sites; D016466:CHO Cells; D050260:Carbohydrate Metabolism; D002241:Carbohydrates / Q000737:chemistry; D006224:Cricetinae; D019040:E-Selectin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004815:Epidermal Growth Factor / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D019041:L-Selectin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008024:Ligands; D015394:Molecular Structure; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
D002241:Carbohydrates; D019040:E-Selectin; D008024:Ligands; D011993:Recombinant Fusion Proteins; D019041:L-Selectin; D004815:Epidermal Growth Factor