Figure 1. Schematic overview of the Spir and MyoV protein fragments used in this study.
The myosin V motor domain and its 6 IQ lever arm is followed by a coiled-coil dimerization region and the C-terminal globular tail domain. The central linker region of Spir connects the N-terminal KIND and four actin binding WH2 domains on one side, with the C-terminal Spir-box (SB) and a membrane binding FYVE-type zinc finger on the other. The newly identified Spir myosin V binding motif (GTBM) is located in the middle of the linker region. The domain boundaries are indicated in the full-length MyoVa (containing exon D (D) or exon F (F)), MyoVb, Spir-1 and Spir-2 proteins. Numbers indicate amino acids. Stars indicate amino acid substitutions. FL, full-length; GTD, globular tail domain; CC, coiled-coil; KIND, kinase non-catalytic C-lobe domain; GTBM, globular tail domain binding motif; SB, Spir-box; LALA, L408,409A substitution. Species abbreviations are Hs, Homo sapiens; Mm, Mus musculus.