Final answer:
Securins are not a class of intermediate filaments. Intermediate filaments include classes such as keratin, vimentin, neurofilaments, and nuclear lamins, which all play roles in cellular structure and function.
Step-by-step explanation:
The class of intermediate filaments that is not part of the group is securins. Intermediate filaments are a diverse group of cytoskeletal elements, with a diameter thicker than microfilaments but thinner than microtubules. They are involved in various cellular functions including maintaining the shape of the cell and anchoring organelles in place, such as the nucleus. Some well-known types of intermediate filaments include keratin, found in hair, skin, and nails; vimentin and vimentin-related proteins found in the cytoplasm; and neurofilaments in neurons. Additionally, nuclear lamins are intermediate filaments that make up the nuclear lamina, which supports the nuclear envelope.