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An examination of five interacting genes involved in the coordination of muscle contraction in Caenorhabditis elegans confirms the sup-9, sup-10 and unc-93 products interact as a protein complex to function in the coordination of muscle contractions. Three new classes of sup-9 alleles, which are the altered-function rubber-band, partial loss-of-function and the dominant suppressor were also identified. The allele-specific interactions revealed by the partial loss-of-function mutation prove that the products of these interacting genes may contact each other physically in a multiple subunit protein complex.

The single-strand conformation polymorphism method was used to study the retinoblastomal (RB1) gene from 12 human retinoblastoma tumors, and all tumors exhibited mutations. In both alleles, a third of the tumors possessed autonomous mutations. The alleles are sporadic because neither was observed in the gene line, concordant with the loss-of-heterozygosity theory of tumors. The most widely seen irregularities were the point mutations, most of which were C yields T transitions, that ordinarily caused the transformation of an arginine codon to a stop codon.

Interaction with Bax is unnecessary for Bcl-x(sub l) to inhibit apoptosis. Mutations of residues in Bcl-x(sub l), that bind to Bax or Bak, reduce its inhibitory activity to a small extent. Site-specific mutagenesis indicate that the amino acids required for the suppression of Sindbis virus-induced cell death by Bcl-x(sub l) are in the Bcl-2-homology regions 1 and 2. The amino acids necessary for the Bcl-x(sub l) activity are different from those necessary for Bcl-2 function.

Genetic mutations and subsequent studies of the genes that cause achondroplasia in individuals reveal recurring missense mutations in a CpG doublet of the transmembrane region of the fibroblast-growth factor receptor-3 (FGFR3) in 17 sporadic and 6 unassociated familial types of achondroplasia. The mutant genotype separately groups with the disease in the observed families. The FGFR3 gene is responsible for achondroplasia, as a mutation of a single amino acid in the transmembrane region of FGFR3 initiates a skeletal growth defect.

A study of the production of missense mutations influencing Asp-161 and Ser-163 in the S subunit of F1F0 ATP synthase, revealed that abolition of enzyme activity resulted from a delta-Asp-160 to Pro substitution, even though a majority of substitutions facilitated significant enzyme function. A structural breakdown modifying the enzyme complex was responsible for the lack of activity. The synthase function probably did not recognize any specific amino acids in the delta subunits.

A graph theoretical method is used to predict the important amino acid residues for further mutation studies of the Dps trimers from Mycobacterium smegmatis. It is shown how the F47 residue is crucial for dodecamerization.

In a screen for mouse mutations with dominant behavioral anomalies, we identified Wheels, a mutation associated with circling and hyperactivity in heterozygotes and embryonic lethality in homozygotes. Mutant Wheels embryos die at E10.5-E11.5 and exhibit a host of morphological anomalies which include growth retardation and anomalies in vascular and hindbrain development. The latter includes perturbation of rhombomeric boundaries as detected by Krox20 and Hoxb1. PECAM-1 staining of embryos revealed normal formation of the primary vascular plexus. However, subsequent stages of branching and remodeling do not proceed normally in the yolk sac and in the embryo proper. To obtain insights into the circling behavior, we examined development of the inner ear by paint-filling of membranous labyrinths of Wh1/+ embryos. This analysis revealed smaller posterior and lateral semicircular canal primordia and a delay in the canal fusion process at E12.5. By E13.5, the lateral canal was truncated and the posterior canal was small or absent altogether. Marker analysis revealed an early molecular phenotype in heterozygous embryos characterized by perturbed expression of Bmp4 and Msx1 in prospective lateral and posterior cristae at E11.5. We have constructed a genetic and radiation hybrid map of the centromeric portion of mouse Chromosome 4 across the Wheels region and refined the position of the Wheels locus to the ~1.1-cM region between D4Mit104 and D4Mit181. We have placed the locus encoding Epha7, in the Wheels candidate region; however, further analysis showed no mutations in the Epha7-coding region and no detectable changes in mRNA expression pattern. In summary, our findings indicate that Wheels, a gene which is essential for the survival of the embryo, may link diverse processes involved in vascular, hindbrain, and inner ear development, [C] 2001 Academic Press Key Words: mouse; ENU mutagenesis; vascular development; angiogenesis; inner ear; Bmp4; Eph.

Mutations in the subunits of three heterodimeric prenyltransferases and an escort protein (REP) trace the role of MAD2 and BET2 genes of yeast during prenylation of Rab protein. MAD2 exemplifies rat rab GGTase alpha protein while 51% of BET2 amino acid sequences bears a homology with rat Rab GGTase-beta. Rab proteins control vesicular fusion during secretion and endocytosis. Farnesylation in these proteins occurs at the cysteine residue of a carboxy terminal CAAX motif. Rab prenylation models cooperative interaction between molecular biology and genetics.