pacman-key --list-sigs Jakob

gpg: Note: trustdb not writable
pub   rsa2048 2010-06-26 [SC]
      2612B04099DBD9B9A3DD92A0456C7A9B91B842AE
uid           [  full  ] Jakob Gruber <jakob.gruber@gmail.com>
sig 3        456C7A9B91B842AE 2010-06-26  Jakob Gruber <jakob.gruber@gmail.com>
sig          3348882F6AC6A4C2 2011-11-20  Pierre Schmitz (Arch Linux Master Key) <pierre@master-key.archlinux.org>
sig          BA1DFB64FFF979E7 2011-12-13  Allan McRae (Arch Linux Master Key) <allan@master-key.archlinux.org>
sig          A88E23E377514E00 2015-12-23  Florian Pritz (Arch Linux Master Key) <florian@master-key.archlinux.org>
sub   rsa2048 2010-06-26 [E]
sig          456C7A9B91B842AE 2010-06-26  Jakob Gruber <jakob.gruber@gmail.com>