Answer the following question given this paragraph: 

Transmembrane proteins span the entire plasma membrane. Their function is mainly to regulate the transport of specific molecules across the membrane. There are two basic types of transmembrane proteins, alpha-helical and beta-barrels, which are discussed in Organic Compounds: Proteins (Advanced) .


Q: What proteins span the entire plasma membrane?

 Choices:

- sequence

- amino acids

- cytoplasm

- transmembrane

A:
transmembrane
