Final answer:
Thrombopoietin is the protein that regulates platelet production, and it is produced mainly by the liver.
Step-by-step explanation:
The protein that controls platelet production is known as thrombopoietin, which is a glycoprotein hormone. Thrombopoietin is produced primarily by the liver and to a lesser extent by the kidneys. This hormone stimulates the development of megakaryocytes, which are large cells in the bone marrow, into platelets. Platelets are critical for the blood clotting process and are released into the bloodstream to perform their role in hemostasis.