Final answer:
Troponin is not a part of the smooth muscle contraction process; instead, smooth muscle utilizes calmodulin, along with calcium ions, myosin light chain kinase, and myosin ATPase, to mediate muscle contractions.
Step-by-step explanation:
Within the smooth muscle contraction process, the component that is not a part of this process is troponin. Smooth muscle cells do not contain troponin; instead, cross-bridge formation is regulated by the protein calmodulin. When external calcium ions pass through the sarcolemma's opened calcium channels and additional calcium is released from the sarcoplasmic reticulum (SR), they bind to calmodulin. The calcium-calmodulin complex activates myosin light chain kinase, leading to the phosphorylation of myosin heads by converting adenosine triphosphate (ATP) to adenosine diphosphate (ADP) and an inorganic phosphate (Pi), which then allows the myosin heads to interact with actin, facilitating muscle contraction.
Other key processes in smooth muscle contraction include the activation of myosin ATPase for energy transfer and the fact that myosin binds to actin to initiate the contraction. The myosin light chain kinase plays a critical role in this process by phosphorylating myosin, but the tropomyosin complex is not involved as it is in skeletal and cardiac muscles. These differences highlight the unique mechanisms behind smooth muscle contraction compared to striated muscle.