List the functions of proteins in the text area below.

Proteins serve a wide range of functions in biological systems, each crucial for maintaining life. Here are some of the primary functions of proteins:

1. Structural Support: Proteins like collagen and keratin provide structural support to cells and tissues, maintaining their shape and integrity.

2. Enzymatic Activity: Many proteins function as enzymes, catalyzing biochemical reactions that are essential for metabolism and other cellular processes.

3. Transport and Storage: Proteins such as hemoglobin transport oxygen in the blood, while others store essential ions and molecules.

4. Cell Signaling: Proteins are involved in cell signaling pathways, acting as receptors and messengers to transmit signals within and between cells.

5. Immune Response: Antibodies are proteins that recognize and neutralize foreign invaders like bacteria and viruses.

6. Movement: Muscle proteins like actin and myosin are responsible for muscle contraction and movement.

7. Regulation of Gene Expression: Some proteins bind to DNA and regulate the transcription of genes, influencing cell function and development.

8. Hormonal Functions: Certain proteins act as hormones, which are chemical messengers that regulate physiological processes.

These diverse functions highlight the versatility and importance of proteins in biological systems.