The detailed entries of the Imprinted Gene Catalogue database were created by Benjamin Tycko, Columbia University, New York and are updated by Ian Morison


 

Detailed entry for Gene:

Rasgrf1
Grf1

Chromosome:

Human Chr15q23-q24
Mouse Chr9

Links:

OMIM

Imprinting:

Maternal allele silenced, paternal allele active in multiple mouse tissues, including brain (Shibata H et al, 1998; Plass C et al, 1996; Pearsall RS et al, 1999; Brambilla R et al, 1997); human data not available.

Gene Product:

Rasgrf1 encodes a guanine nucleotide exchange factor (GEF), which participates in Ras and Ras-family signaling (Overbeck AF et al, 1995). RasGrf is highly expressed in the brain (Ferrari C et al, 1994; Finkbeiner S et al, 1998). Its protein sequence includes a Dbl-homology domain, PH-domain and Ras-GEF domain.

Functional Data:

The RasGrf1 protein promotes the GTP-bound state of Ras-family members, which are low molecular weight G-proteins (Overbeck AF et al, 1995; Graham SM et al, 1996; Innocenti M et al, 1999). Knockout mice lacking RasGrf1 are viable and, consistent with imprinting, the -mat/+pat heterozygotes lack RasGrf1 protein in brain (Brambilla R et al, 1997). The mice show memory or learning deficits, suggesting involvement of RasGrf1 in synaptic remodeling (Brambilla R et al, 1997; Orban PC et al, 1999). In addition, the RasGrf1-null mice are ~15% smaller than littermate controls; this effect is small in magnitude, but it has been reproduced in two independent laboratories (Itier JM et al, 1998; Orban PC et al, 1999). This smaller size has been attributed to reduced growth hormone secretion (Itier JM et al, 1998).

 

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