text: In sperm cells, a specific type of these proteins known as catsper is of the "two-pore" variety.
full_question: In sperm cells, a specific type of these proteins known as catsper is of the "two-pore" variety. In one of these proteins, the five residue sequence TVGYG forms a "selectivity filter" that removes a hydration shell. In another of them, the highly-conserved S4 segment acts as a "sensor." Four types of conotoxin from cone snails and (*) tetrodotoxin from puffer fish block these proteins. The patch-clamp technique can be used to study these proteins, one type of which activates during the period of hyperpolarization. Two "voltage- gated" examples of these proteins keep the resting potential of a neuron at -70 mV. For 10 points, name these proteins that control the flow of charged atoms like sodium across a cell membrane.
first_sentence: In sperm cells, a specific type of these proteins known as catsper is of the "two-pore" variety.
raw_answer: ion channels [prompt on membrane proteins; prompt on integral membrane proteins; prompt on channels; accept TRPs; accept transient receptor potential channels; accept sodium channels; accept potassium channels; accept ionotropic receptors]