The KIND domain (kinase non-catalytic C-lobe domain) evolved from a catalytic protein kinase fold and functions as an interaction domain [1]. In SPIRE1 (protein spire homologue 1) this domain interacts with FMN2 (formin-2) [2-3].

1: The KIND module: a putative signalling domain evolved from the C lobe of the protein kinase fold. Ciccarelli FD, Bork P, Kerkhoff E; Trends Biochem Sci. 2003;28:349-352. PMID:12877999

2: Structure and function of the interacting domains of Spire and Fmn-family formins. Vizcarra CL, Kreutz B, Rodal AA, Toms AV, Lu J, Zheng W, Quinlan ME, Eck MJ; Proc Natl Acad Sci U S A. 2011;108:11884-11889. PMID:21730168

3: Molecular basis of actin nucleation factor cooperativity: crystal structure of the Spir-1 kinase non-catalytic C-lobe domain (KIND)*formin-2 formin SPIR interaction motif (FSI) complex. Zeth K, Pechlivanis M, Samol A, Pleiser S, Vonrhein C, Kerkhoff E; J Biol Chem. 2011;286:30732-30739. PMID:21705804