The cytoplasmic area of pseudorabies virus (PRV) glycoprotein B (gB) contains three putative internalization motifs. with the cellular clathrin-associated AP-2 adaptor complex and that this colocalization depends on the YQRL motif. In addition, by PP121 coimmunoprecipitation assays, we found that during both spontaneous and antibody-dependent internalization, PRV gB actually interacts with AP-2, and that efficient conversation between gB and AP-2 required an intact YQRL motif. Collectively, these findings demonstrate for the first time that during internalization of an alphaherpesvirus envelope protein, i.e., PRV gB, a specific amino acid sequence in the cytoplasmic tail of the protein interacts with AP-2 and may constitute a common AP-2-mediated mechanism of internalization of alphaherpesvirus envelope proteins. Pseudorabies computer virus (PRV), a swine alphaherpesvirus closely related to the human pathogens herpes simplex virus (HSV) and varicella-zoster computer virus (VZV), is the causative agent of Aujeszky’s disease (4, 24). Its genome encodes at least 11 glycoproteins, which have homologs in other herpesviruses (24). In PRV-infected cells, recently synthesized glycoproteins travel in the endoplasmic reticulum via the Golgi towards the plasma membrane (25). These glycoproteins play essential jobs in the viral lifestyle cycle, aswell such as the pathogenesis of PRV attacks (9, 29). Oddly enough, many alphaherpesvirus-encoded cell surface-associated envelope glycoproteins have already been reported to become internalized, either spontaneously or upon binding of antigen-specific antibodies (12, 13, 17, 32, 35, 36, 44). The natural function of spontaneous internalization in the pathogen life cycle isn’t yet fully grasped, even though some hypothetical jobs have been suggested (analyzed in guide 9), like the feasible participation of internalization in providing the viral cell surface area proteins to a particular area, where viral envelopment occurs; in redirecting viral protein to particular membrane areas (such as the apical, lateral, or basal surfaces of polarized cells); or in immune evasion. Antibody-dependent internalization of viral cell surface proteins may also be implicated in immune evasion, since it has been shown to decrease the efficiency of antibody-dependent lysis of PRV-infected cells (49). Recently, several groups reported around the amino acid sequence motifs involved in the internalization of different alphaherpesvirus envelope glycoproteins. Two types of motifs, located in the cytoplasmic tails of these viral proteins, have been shown to be of predominant importance: tyrosine-based YXX-type motifs (where Y stands for tyrosine, X stands for any amino acid, and PP121 stands for PP121 any heavy hydrophobic amino acid) and LL (dileucine) motifs. Spontaneous internalization of PRV glycoprotein E (gE) requires an intact YTSL motif (where T stands for threonine and S stands for serine) in its cytoplasmic tail (45), and internalization of PRV gB requires the C-terminal 29 amino acids of the gB cytoplasmic domain name, which contain an LL motif and a YQRL motif (where Q stands for glutamine and R stands for arginine) (32). In a previous study, it was shown that this gB membrane-distal YQRL motif at positions 902 to 905, but not the membrane-proximal YMSI motif at positions 864 to 867 (where M stands for methionine and I stands for isoleucine) or the LL doublet at positions 887 and 888, is critical for efficient antibody-mediated internalization of PRV cell surface proteins (13). In agreement with these findings, mutation of the HSV gB membrane-distal YSPL motif (where P stands for proline), but not mutation of the membrane-proximal YMAL motif (where A stands PP121 for alanine) or the LL motif, was found to abrogate internalization of HSV gB (11). The internalization of some VZV-encoded glycoproteins has also been shown to depend on either a YXX motif or an LL motif. Indeed, internalization of VZV gB, gE, and gH requires, respectively, a YSRV (where V stands for valine), a YAGL (where G stands for glycine), or a YNKI (where N stands for asparagine and K stands IGF1 for lysine) motif located in the respective cytoplasmic domains, while internalization of VZV gI is dependent on an LL motif (3, 17, 35, 36, 37). Thus, the internalization of many alphaherpesvirus envelope proteins is usually mediated by related tyrosine-based.