 Other proteins that serve structural functions are motor proteins such as myosin , kinesin , and dynein , which are capable of generating mechanical forces . These proteins are crucial for cellular motility of single celled organisms and the sperm of many multicellular organisms which reproduce sexually . They also generate the forces exerted by contracting muscles and play essential roles in intracellular transport . 
 Other proteins <a href='null_relcl' title='1'><mark>that</mark></a>serve structural functions <a href='drop_aux' title='2'><mark>are</mark></a>motor proteins such as myosin , kinesin , and dynein , which <a href='drop_aux' title='3'><mark>are</mark></a>capable of generating mechanical forces . These proteins <a href='drop_aux' title='4'><mark>are</mark></a>crucial for cellular motility of single celled organisms and the sperm of many multicellular organisms which reproduce sexually . They also generate the forces exerted by contracting muscles and play essential roles in intracellular transport . 
Other proteins serve structural functions motor proteins such as myosin , kinesin , and dynein , which capable of generating mechanical forces . dem proteins crucial for cellular motility of single celled organisms and da sperm of many multicellular organisms which reproduce sexually . They also generate tdaforces exerted by contracting muscles and play essential roles in intracellular transport .