Identification of equine P-selectin glycoprotein ligand-1 (CD162).
P-selectin glycoprotein ligand-1 (PSGL-1, CD162) is a dimeric, mucin-like, transmembrane glycoprotein constitutively expressed on leukocytes. A high baseline level of P-selectin expression in circulating equine platelets suggests a primed state toward inflammation and thrombosis via P-selectin/PSGL-1 adhesion. To investigate the potential role of equine P-selectin in these events, we first identified the cDNA sequence of equine PSGL-1 (ePSGL-1) using degenerate PCR and RACE-PCR and then compared the predicted sequence with that of human PSGL-1 (hPSGL-1). ePSGL-1 protein subunit is predicted to be 43 kDa and composed of 420 amino acids with a predicted 18-amino-acid signal sequence showing 78% homology to hPSGL-1. Previously published work has shown that binding of P-selectin requires sulfation of at least one of three tyrosines and O-glycosylation of one threonine in the N-terminus of human PSGL-1. However, the corresponding domain in ePSGL-1, spanning residues 19-43, contains only one tyrosine in the vicinity of two threonines at positions 25 and 41. ePSGL-1 contains 14 threonine/serine-rich decameric repeats as compared to hPSGL-1 which contains 14-16 threonine-rich decameric repeats. The transmembrane and cytoplasmic domains display 91% and 74% homology to corresponding human PSGL-1 domains, respectively. In summary, there is 71% homology in comparing the open reading frame (ORF) of ePSGL-1 with that of hPSGL-1. The greatest homologies between species exist in the transmembrane domain and cytoplasmic tail while substantial differences exist in the extracellular domain.
Xu
Jin
J
Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin, Madison, Wisconsin, 53706-1102, USA.
Lasry
Joëlle B
JB
Svaren
John
J
Wagner
Bettina
B
Darien
Benjamin J
BJ
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D006736:Horses / Q000235:genetics; D006801:Humans; D008024:Ligands; D008562:Membrane Glycoproteins / Q000097:blood / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D008969:Molecular Sequence Data; D019007:P-Selectin; D016133:Polymerase Chain Reaction; D017385:Sequence Homology
D008024:Ligands; D008562:Membrane Glycoproteins; D019007:P-Selectin; C084882:P-selectin ligand protein