Microtubule “Plus-End-Tracking Proteins” Scott C. Schuyler, David Pellman  Cell  Volume 105, Issue 4, Pages 421-424 (May 2001) DOI: 10.1016/S0092-8674(01)00364-6

Figure 1 Plus-End Treadmilling (A) CLIP-170 (in green) binds the polymerizing plus end of the MT (at the right) and remains bound until it is released behind the region of growth. (B) Fluorescent speckle analysis (FSA). The release of fluorescently tagged CLIP-170 creates a nonuniform “fluorescent speckle” pattern that serves as a “bar code” which marks the position of bound GFP-CLIP-170 relative to the MT. FSA demonstrates that as an MT plus end polymerizes (from top to bottom), the bound GFP-CLIP-170 does not slide. If, for example, a MT-based motor transported +TIPs to the MT plus end, the “bar code” would slide to the right. (C) Three models for +TIP binding to the MT plus end. +TIPs are shown in green, the GTP-bound form of α/β-tubulin dimers is in red, and the GDP-bound form of α/β-tubulin dimers is in gray Cell 2001 105, 421-424DOI: (10.1016/S0092-8674(01)00364-6)