What protein in red blood cells is responsible for oxygen transport?

The protein responsible for oxygen transport in red blood cells is hemoglobin. Hemoglobin is a globular protein that has a high affinity for oxygen, allowing it to bind oxygen in the lungs and transport it to tissues throughout the body. Each hemoglobin molecule can carry up to four molecules of oxygen, making it highly efficient at oxygen transport.

In the context of the other proteins listed: albumin primarily serves as a carrier for various substances in the blood, including hormones and drugs, and helps maintain oncotic pressure. Myoglobin, while it is an oxygen-binding protein found in muscle tissue, does not play a role in transporting oxygen in the blood; instead, it stores oxygen for use in muscle cells. Collagen is a structural protein that provides support and strength to various tissues but is not involved in oxygen transport. Thus, hemoglobin stands out as the key protein in red blood cells specifically tasked with carrying oxygen.