Figure 2.
Panel A: Illustration of a cytoneme containing F actin, calcium ions, signaling proteins, rough endoplasmic reticulum, and a mitochondrion. Panel B: Illustration of a thick tunneling nanotube containing microtubules, F actin, calcium ions, proteins, viruses, vesicles, rough endoplasmic reticulum, mitochondria, and a surfing bacterium.
Schematic diagram depicting the contents of a cytoneme and a thick TNT. (A) Cytonemes contain a core of F-actin filaments with various ions, including calcium fluxes and signaling molecules such as WNT proteins; however, some can also contain mitochondria and rough ER in bulges. (B) The contents of thick TNTs always include long structural F-actin filaments, but they can also contain microtubules and multiple other cytoplasmic components. Contents can include not only ions and signaling molecules and/or other proteins (normal or pathogenic), as well as viruses, vesicles of various types and sizes, rough ER, and mitochondria; in addition, some bacteria can “surf” along the surface of TNTs. The contents are drawn roughly to scale.