Gp stands for 'Glycoproteins' and the numbers after it are the group of proteins attached to it.
The virus of HIV follows the mechanism in which GP120 helps in attaching with CD4 receptors of helper T cells.
HIV envelope glycoprotein Gp120 that mediates the fusion of the viral envelope with the target cell membrane.
This is done by binding to CD4 and a chemokine receptor 30.
Both CCR5 and CXCR4 physically associate with CD4 and Gp120, and also known as ‘HIV co-receptors’.