Glycoprotein 100, gp100 or Melanocyte protein PMEL is 661 amino acids long and is a type I transmembrane glycoprotein enriched in melanosomes, which are the melanin-producing organelles in melanocytes. This protein is involved in melanosome maturation. The Human HLA-A*0201 gp100 (YLEPGPVTA) complex Protein is a complex of HLA-A*0201 of? the MHC Class I, B2M and YLEPGPVTA peptide of? the gp100.