Molecular basis of loss-of-function mutations in the glp-1 gene of Caenorhabditis elegans.
The glp-1 gene encodes a membrane protein required for inductive cell interactions during development of the nematode Caenorhabditis elegans. Here we report the molecular characterization of 15 loss-of-function (lf) mutations of glp-1. Two nonsense mutations appear to eliminate glp-1 activity; both truncate the glp-1 protein in its extracellular domain and have a strong loss-of-function phenotype. Twelve missense mutations and one in-frame deletion map to sites within the repeated motifs of the glp-1 protein (10 epidermal growth factor [EGF]-like and 3 LNG repeats extracellularly and 6 cdc10/SWI6, or ankyrin, repeats intracellularly). We find that all three types of repeated motifs are critical to glp-1 function, and two individual EGF-like repeats may have distinct functions. Intriguingly, all four missense mutations in one phenotypic class map to the N-terminal EGF-like repeats and all six missense mutations in a second phenotypic class reside in the intracellular cdc10/SWI6 repeats. These two clusters of mutations may identify functional domains within the glp-1 protein.
Kodoyianni
V
V
Department of Biochemistry, University of Wisconsin-Madison 53706.
Maine
E M
EM
Kimble
J
J
D000595:Amino Acid Sequence; D000818:Animals; D017487:Ankyrins / Q000737:chemistry; D001483:Base Sequence; D017173:Caenorhabditis elegans / Q000235:genetics*; D029742:Caenorhabditis elegans Proteins; D003001:Cloning, Molecular; D004815:Epidermal Growth Factor / Q000737:chemistry; D017238:Genes, Helminth; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics*; D010641:Phenotype; D051880:Receptors, Notch; D012091:Repetitive Sequences, Nucleic Acid; D015183:Restriction Mapping
D017487:Ankyrins; D029742:Caenorhabditis elegans Proteins; C060620:Glp-1 protein, C elegans; D008562:Membrane Glycoproteins; D051880:Receptors, Notch; D004815:Epidermal Growth Factor