RT Journal Article SR Electronic T1 EB1 binding provides a diffusion trap mechanism regulating STIM1 localization and Ca2+ signaling JF bioRxiv FD Cold Spring Harbor Laboratory SP 224162 DO 10.1101/224162 A1 Chi-Lun Chang A1 Yu-Ju Chen A1 Jen Liou YR 2017 UL http://biorxiv.org/content/early/2017/11/22/224162.abstract AB The endoplasmic reticulum (ER) Ca2+ sensor STIM1 forms oligomers and translocates to ER-plasma membrane (PM) junctions to activate store-operated Ca2+ entry (SOCE) following ER Ca2+ depletion. STIM1 also directly interacts with end binding protein 1 (EB1) at microtubule (MT) plus-ends and resembles comet-like structures during time-lapse imaging. Nevertheless, the role of STIM1-EB1 interaction in regulating SOCE remains unresolved. Using live-cell imaging combined with pharmacological perturbation and a reconstitution approach, we revealed that EB1 binding constitutes a diffusion trap mechanism restricting STIM1 targeting to ER-PM junctions. We further showed that STIM1 oligomers retain EB1 binding ability in ER Ca2+-depleted cells. EB1 binding delayed the translocation of STIM1 oligomers to ER-PM junctions and recaptured STIM1 to prevent excess SOCE and ER Ca2+ overload. Thus, the counterbalance of EB1 binding and PM targeting of STIM1 shapes the kinetics and amplitude of local SOCE in regions with growing MTs, and contributes to precise spatiotemporal regulation of Ca2+ signaling crucial for cellular functions and homeostasis.Summary STIM1 activates store-operated Ca2+ entry (SOCE) by translocating to endoplasmic reticulum-plasma membrane junctions. Chang et al. revealed that STIM1 localization and SOCE are regulated by a diffusion trap mechanism mediated by STIM1 binding to EB1 at growing microtubule ends.CT,C-terminal region;EB1,end binding protein 1;ECB,extracellular buffer;EF-SAM,EF hand-sterile α motif;ER,endoplasmic reticulum;FKBP,FK506-binding protein; iMAPPER, inducible MAPPER;IP3,inositol 1,4,5-triphosphate;MAPPER,membrane-attached peripheral ER;MT,microtubule;NocZ,nocodazole;PB,polybasic motif;PM,plasma membrane;PIP2,phosphatidylinositol 4,5-bisphosphate;SERCA,sarco/endoplasmic reticulum Ca2+-ATPaseSOCE,store-operated Ca2+ entry;STIM1,stromal interaction molecule 1;TG,thapsigargin;TIRF,total internal reflection fluorescence