pins (Partner of Inscuteable / Rapsynoid; Q9VB22) notes

Identity

• GPSM-family protein (LGN/AGS3/GPSM2 orthologue): N-terminal TPR repeats and three C-terminal GoLoco motifs (UniProt Q9VB22 InterPro IPR003109 GoLoco_motif; IPR019734 TPR_rpt).

Literature journal

• Discovered as Rapsynoid, a Galphai two-hybrid partner PMID:10875939. raps mutant neuroblasts lose Insc asymmetry and divide into equal-sized daughters PMID:10875939.
• Pins stabilizes the apical complex and binds Insc via its TPRs [PMID:12571286 "Pins acts to stabilize the apical complex during neuroblast divisions"; "its N-terminal tetratricopeptide repeats can directly interact with the asymmetric localization domain of Insc"]. Mouse LGN rescues pins PMID:12571286.
• Pins/Galphai and Baz/aPKC act in parallel to control spindle geometry and daughter size PMID:12526793.
• GoLoco proteins Pins and Loco act as Galphai GDIs to release Gbetagamma PMID:15937221.
• Pins directly binds Mud (NuMA) and recruits it apically [PMID:16648843 "Pins directly binds, and coimmunoprecipitates with, the NuMA-related Mushroom body defect (Mud) protein"; "Pins recruits Mud to the neuroblast apical cortex"].
• Autoinhibited closed state; Galphai binding to GoLocos 2/3 opens the TPRs to Mud [PMID:17726110 "Pins forms a \"closed\" state via intramolecular GoLoco-tetratricopeptide repeat (TPR) interactions, which regulate Mud binding"].
• Canoe binds the Pins TPR domain to activate the Pins/Mud/dynein pathway PMID:22024168.
• Crystal structure of Pins TPR with Insc; Insc and NuMA compete PMID:22171003.
• Microtubule/Khc-73/Dlg pathway also polarizes Pins/Galphai PMID:16377571.
• Go (Galphao) binds Pins in SOP cells PMID:16617104.
• pins mutant brain tissue grows as tumours after transplantation PMID:16142234 - indirect consequence of altered asymmetric division.
• Pins enriches Rok and Pkn apically to bias myosin PMID:28712722.

Curation thoughts

• Core MF: GoLoco-mediated Galphai-GDP binding / GDI activity, and TPR-mediated scaffolding of Mud/Insc/Canoe (adaptor).
• Generic protein binding IPIs replaced/kept as non-core; IEA GTPase regulator activity refined to GDI activity.
• Determinant localization and tumour/proliferation terms are downstream/indirect.

Deep research (falcon) additions

• Falcon report (pins-deep-research-falcon.md) agrees: Pins is a cortical adaptor for spindle positioning ["Pins binds Mud directly through its TPR region."]. It also notes tissue specificity: Pins-null wing-disc cells keep normal division orientation (Bergstralh et al. 2016, doi:10.1242/dev.135475; not in local cache), and an Aurora-A/Dlg/Khc73 branch from the Pins linker.