The nutrients enters into the cytoplasm through _________ proteins.

These proteins transport specific substances from one part of body to the others. Most familiar is haemoglobin of red blood cells (erythrocytes or RBCs) of vertebrates. Serum albumin transports fatty acids in blood from fatty tissues to other tissues. Transferrin protein transports iron, and certain other proteins transport steroid hormones, drugs, toxins, etc. in blood. Transport proteins of plasma membrane transport materials across the membrane. For instance, glucose and amino acids enter into all cells through membrane transport proteins.