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Horm Metab Res 1978; 10(4): 331-336
DOI: 10.1055/s-0028-1093425
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© Georg Thieme Verlag KG Stuttgart · New York

Effects of Phospholipase A and Triton X-100 on Guanylate Cyclase Activity in Mammary Gland Homogenates from Mice

J. A. Rillema , B. E. Linebaugh
  • Department of Physiology, Wayne State University, School of Medicine, Detroit, Michigan 48201, USA
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Publication Date:
23 December 2008 (online)

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Abstract

The effects of a variety of agents on guanylate cyclase activity were tested in broken cell preparations of mammary glands from midpregnant mice. Of the agents tested, only phospholipase A, triton X-100, and an impure egg lysolecithin preparation enhanced the activity of guanylate cyclase in mammary gland homogenates; other agents, including sodium azide and phospholipase C, and purified egg lysolecithin had no effect.

Phospholipase A increased the activity of guanylate cyclase in the 150,000 g pellet fractions of mammary gland homogenates, but did not consistently enhance guanylate cyclase in the 150,000 g supernatant fractions. Phospholipase A did not appear to enhance guanylate cyclase activity by solubilizing the enzyme from the 150,000 g pellet.

Triton X-100, in contrast, appeared to act by solubilizing guanylate cyclase from the material present in the 150,000 g pellet. Triton X-100 increased by several fold guanylate cyclase activity in the tissue homogenates and the 150,000 g pellets, but did not consistently enhance enzyme activity in the 150,000 g supernatant. Triton X-100 had no effect on the apparent Km of guanylate cyclase.

Key words

Mammary Gland - Guanylate Cyclase - Phospholipase A - Triton X-100 - Lysolecithin