Two G protein oncogenes in human endocrine tumors

Article Abstract:

Changes, or mutations, in the DNA (deoxyribose nucleic acid) sequence in tumors of the pituitary gland, which secretes growth hormone, cause the alpha chain, one of the components of a G protein (guanine nucleotide binding protein) to become an oncogene. An oncogene is a gene that can cause abnormal growth of cells. G proteins are molecules that are involved in the transmission of a signal from the outside to the inside of the cell, leading to cell activation. The changes, which affect either of two amino acids (the building blocks of proteins), activate the oncogene by inhibiting the removal of guanosine triphosphate. The G protein then remains active, leading to an abnormal state of activation and cell growth. This oncogene is called gsp and was found in 18 out of 42 pituitary tumors that secret growth hormone, and in an adenoma (glandular tumor) of the thyroid gland. Other tumors were examined to see if similar changes could activate other G proteins. Comparable types of change were found in a type of G protein in 3 out of 11 tumors of the cortex of the adrenal gland, and in 3 out of 10 tumors of the ovary. This mutation is known as gip2. Thus, in human endocrine tumors, various G proteins may be mutated such that they become oncogenic. (Consumer Summary produced by Reliance Medical Information, Inc.)

Physiological aspects, Genetic aspects, Identification and classification, Cancer, Cancer genetics, Mutation (Biology), Mutation, Oncogenes, Endocrine gland tumors

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Pieces of the true grail: a G protein finds its target

Article Abstract:

A new crystal structure has been reported for the alpha subunit of G(sub s) complex with adenylyl cyclase. The three dimensional picture is suggestive of how other protein regulators interact with the enzyme and may eventually lead to the understanding of how hormones stimulate the production of cyclic AMP.

Models, Analysis, Proteins, Molecules

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Trimeric G proteins: surprise witness tells a tale

Article Abstract:

Researchers discovered that G-alpha monomers attach to one another to form endless polymers in crystals of the guanosine diphosphate (GDP) form of alpha-i1. The observation may reveal how receptors with G-beta-gamma precipitate GDP release and G protein activation.

Research, Cellular signal transduction

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