During myelination in the central nervous system, proteins arising from the gene in the oligodendrocyte lineage (golli) participate in diverse events in signal transduction and gene regulation. One of the interacting partners of the Golli-isoform BG21 was discovered by yeast-2-hybrid means and was denoted the Golliinteracting-protein (GIP). In subsequent in vitro studies of recombinant murine GIP, it was not possible to produce a full-length version of recombinant murine rmGIP in functional form under native conditions, primarily because of solubility issues, necessitating the study of a hexahistidine-tagged, truncated form ANrmGIP. This protein is an acidic phosphatase belonging to the family of RNA-polymerase-2, small-subunit, C-terminal phosphatases (SCP1), and studies of the human ortholog hSCP1 have also been performed on truncated forms. Here, a new SUMO-expression and purification protocol has been developed for the preparation of a functional, full-length mSCP1/GIP (our nomenclature henceforth), with no additional purification tags. Both full-length mSCP1/GIP and the truncated murine form (now denoted AN-rmSCP1/GIP) had similar melting temperatures, indicating that the integrity of the catalytic core perse was minimally affected by the N-terminus. Characterization of mSCP1/GIP activity with the artificial substrate p-NPP (p-nitrophenylphosphate) yielded kinetic parameters comparable to those of AN-rmSCP1/GIP and the truncated human ortholog AN-hSCP1. Similarly, mSCP1/GIP dephosphorylated a more natural CTD-peptide substrate (but not protein kinase C-phosphorylated BG21)with comparable kinetics to AN-hSCP1. The successful production of an active, full-length mSCP1/GIP will enable future evaluation of the functional role of its N-terminus in protein protein interactions (e.g., BG21) that regulate its phosphatase activity. (C) 2014 Elsevier Inc. All rights reserved.