Final answer:
Type I fusion proteins are used by enveloped viruses like HIV to fuse with host cell membranes and release their genetic material into the cell. They utilize special glycoproteins to bind to cell receptors for entry.
Step-by-step explanation:
Type I fusion proteins are employed by enveloped viruses, such as HIV, to enter host cells by fusing their viral envelope with the host cell membrane. This process is distinct from receptor-mediated endocytosis and occurs only with enveloped virions, facilitating the release of the virus's genome and capsid into the cell's cytoplasm for replication. These viruses use glycoproteins embedded in their envelopes to specifically bind to receptors on the cell, like HIV using the CD4 molecule on T lymphocytes, which provide a gateway for the viral entry.
Enveloped viruses, such as HIV, use Type I fusion proteins to facilitate fusion of their envelope with the host cell's plasma membrane. This allows the virus to release its genetic material into the host cell and initiate replicatio