RAPID ISOLATION OF G-ALPHA(13) FROM BOVINE BRAIN MEMBRANES - SUPPORTIVE EFFECT OF ETHYLENE-GLYCOL

G(13) belongs to the G(12)-subfamily of heterotrimeric regulatory G-pr oteins. Employing specific antibodies, we isolated G alpha(13) from bo vine brain by a four-step purification protocol combining conventional and affinity chromatography. The use of ethylene glycol as a protecti ve agent influenced the elution properties of G alpha(13) markedly. On ly in the presence of ethylene glycol (30% v/v) a clear separation of G alpha(13) from other G-proteins was achieved during the initial anio n exchange chromatography. This allowed isolation of G alpha(13) by su bunit exchange chromatography on beta gamma-agarose. G alpha(13) was o nly released from immobilized beta gamma-dimers via activation by AMF but not by GTP gamma S, pointing to a poor basal nucleotide exchange o f this protein. In contrast, N-terminally truncated G alpha(13) did no t bind to immobilized beta gamma-dimers. (C) 1994 Academic Press, Inc.