If we consider the many embedded structures of the plasma membrane, the transmembrane proteins that help regulate what enters and exits a cell are essential. They help to maintain homeostasis within the cell and allow for the cell to perform its function. Considering the many different transmembrane proteins that exists and the role in the cell, which of the following is true Group of answer choices

a transmembrane protein that contains a receptor site is controlled by the binding or absence of signaling molecules

all choices are true

a transmembrane protein that serves as a channel and utilizes passive diffusion allows for molecules to move freely through them from high to low concentration

a transmembrane protein that serves as a pump or transporter utilizes active transport and ATP to move molecules against their concentration gradient