Fragmin60 encodes an actin-binding protein with a C2 domain and controls actin Thr-203 phosphorylation in Physarum plasmodia and sclerotia.

We report the isolation of a cDNA clone encoding a 60-kDa protein termed fragmin60 that cross-reacts with fragmin antibodies. Unlike other gelsolin-related proteins, fragmin60 contains a unique N-terminal domain that shows similarity with C2 domains of aczonin, protein kinase C, and synaptotagmins. The fragmin60 C2 domain binds three calcium ions, one with nanomolar affinity and two with micromolar affinity.

Selected BTB/POZ-kelch proteins bind ATP.

Proteins with a bric-à-brac, tramtrack, broad-complex/Poxvirus zinc fingers (BTB/POZ) domain are implicated in a broad variety of biological processes, including DNA binding, regulation of gene transcription and organization of macromolecular structures. Kelch domain containing BTB/POZ proteins like Mayven and Keap1 display limited sequence similarity with the actin-fragmin kinase from Physarum, a protein kinase with a kelch domain. We show that mouse Keap1, a Caenorhabditis elegans protein that we named CKR, and human Mayven bind 5'-p-fluorosulfonyl-benzoyl-adenosine (FSBA), a covalently modifying ATP analogue.