HLA class II histocompatibility antigen gamma chain (HLA-DR antigens-associated invariant chain) (Ia antigen-associated invariant chain) (Ii) (CD antigen CD74) [Cleaved into: Class-II-associated invariant chain peptide (CLIP)]
1_MHRRR 6_ SRSCR 11_ EDQKP 16_ VMDDQ 21_ RDLIS 26_ NNEQL 31_ PMLGR 36_ RPGAP 41_ ESKCS 46_ RGALY 51_ TGFSI 56_ LVTLL 61_ LAGQA 66_ TTAYF 71_ LYQQQ 76_ GRLDK 81_ LTVTS 86_ QNLQL 91_ ENLRM 96_ KLPKP 101_ PKPVS 106_ KMRMA 111_ TPLLM 116_ QALPM 121_ GALPQ 126_ GPMQN 131_ ATKYG 136_ NMTED 141_ HVMHL 146_ LQNAD 151_ PLKVY 156_ PPLKG 161_ SFPEN 166_ LRHLK 171_ NTMET 176_ IDWKV 181_ FESWM 186_ HHWLL 191_ FEMSR 196_ HSLEQ 201_ KPTDA 206_ PPKVL 211_ TKCQE 216_ EVSHI 221_ PAVHP 226_ GSFRP 231_ KCDEN 236_ GNYLP 241_ LQCYG 246_ SIGYC 251_ WCVFP 256_ NGTEV 261_ PNTRS 266_ RGHHN 271_ CSESL 276_ ELEDP 281_ SSGLG 286_ VTKQD 291_LGPVP
1: Plays a critical role in MHC class II antigen processing by stabilizing peptide-free class II alpha/beta heterodimers in a complex soon after their synthesis and directing transport of the complex from the endoplasmic reticulum to the endosomal/lysosomal system where the antigen processing and binding of antigenic peptides to MHC class II takes place. Serves as cell surface receptor for the cytokine MIF
2: Binds to the peptide-binding site of MHC class II alpha/beta heterodimers forming an alpha-beta-CLIP complex, thereby preventing the loading of antigenic peptides to the MHC class II complex until its release by HLA-DM in the endosome
3: Stabilizes the conformation of mature CTSL by binding to its active site and serving as a chaperone to help maintain a pool of mature enzyme in endocytic compartments and extracellular space of antigen-presenting cells (APCs). Has antiviral activity by stymieing the endosomal entry of Ebola virus and coronaviruses, including SARS-CoV-2 (PubMed:32855215). Disrupts cathepsin-mediated Ebola virus glycoprotein processing, which prevents viral fusion and entry. This antiviral activity is specific to p41 isoform (PubMed:32855215)