Selectins are cell membrane glycoproteins that recognize specific glycoconjugates expressed on the surface of cells. Then, selectins adjust cell-cell interactions that are important in inflammation, hemostasis and cancer metastasis. Selectins mediate leukocyte calls to move into the site of inflammation through interactions with activated endothelial cells or endogenous selectin ligands expressed in high endothelial venules. Types of selectins are divided into L-selectin, E-selectin and P-selectin, which are called to CD62L, CD62E, and CD62P, respectively. Each selectin is composed of four regions; the C-type lectin region of N-terminal, the epidermal growth factor (EGF) region, the intracellular C-terminal region, and the hydrophobic transmembrane region. They have similar structures but differ in their binding specificities and tissue distributions. The selectin family commonly recognizes the sialyl Lewis X (sLeX) on carbohydrate structures. Although biological ligands bound to each selectin are different from each other, they commonly bind to P-selectin glycoprotein ligand-1 (PSGL-1) ligand. The PSGL-1 ligand is a glycoprotein promoting cell adhesion in inflammatory responses. If the absence of selectins and their ligands in humans and animals are, should lead to persistent infections and diseases. Selectin family must be considered as a key subject for drug discovery since they have various functions depending on the ligand which they bind to.

Cluster of differentiation (CD) 24 or heat stable antigen 24 (HSA) molecule is a mucin-type glycoprotein attached to the cell surface by glycosylphosphatidylinositol (GPI)-anchor, promoting adhesive interactions between cells or in extracellular matrix. The aim of this study was to determine the not yet fully identified porcine CD24 gene and protein structure using computational analysis and to validate variants reported in exons of CD24 gene using direct sequencing. A total of 59 samples belonging to Yorkshire, Landrace, Berkshire, Jeju black pig and wild boar were used in the study. Human CD24 mRNA sequences were used as a reference and subjected to BLAST searches to retrieve the orthologous expressed sequence tags (ESTs) or cDNA sequences against NCBI and Ensemble databases. Assembled ESTs and retrieved cDNA sequences for the porcine CD24 gene were used for specific BLAST search to determine its genomic structure. We found porcine CD24 gene to consist of two exons and a relatively long intron. Second exon of porcine CD24 gene had a long 3’ untranslated region (UTR) and was very similar to that of human, mouse, rat, and sheep. The sequence homology of porcine CD24 protein was 65.38-84.62%, when analyzed with amino acid sequences of rat, mouse, human, cattle, and sheep CD24 protein. N-terminal signal sequence, O-glycosylation sites and GPI-anchoring signal sites were also predicted in pig, which showed these motifs to be evolutionary conserved across the species. Variant analysis in exonic regions of porcine CD24 among the multiple breeds showed that only second exon contained eight SNPs and three insertions in a 3’ UTR. Taken together, this study reports putative porcine CD24 gene and its protein structure using in silico approaches, which will be helpful for any further functional studies.