Protrusion-associated CCP closure. (A) HPICM topographical images show a cap formation process. The red circles indicate membrane protrusions associated with CCPs. (B) Topographical and fluorescent confocal image pairs show pit formation, growth, steady state, and closure. The formation of a protrusion seen in the topographical image occurs right before pit closure and disappearance of the Clc-EGFP fluorescence (red circles). (C) Example trace of typical CCP depth/cap height and corresponding Clc-EGFP fluorescence changes during pit formation, maturation, and closure with cap formation. (D) Pit depth increase during pit formation (n = 40). (E) Pit cap height increase during cap formation (n = 49). (F) Clc-EGFP fluorescence change during pit nucleation showing growth and steady state (n = 8). (G) Clc-EGFP fluorescence change during pit closure. The shaded region represents cap appearance before pit closure and disappearance of the Clc-EGFP fluorescence (n = 18). (D–G) Error bars represent SD. (H) Formation of a protrusion occurs together with the Abp1-EGFP fluorescence signal increase during pit closure (red circles). (I) Formation of a protrusion occurs together with the GFP-WT-DNM2 fluorescence increase during pit closure (red circles).