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A gap gene is a type of gene involved in the development of the segmented embryos of some arthropods. Gap genes are defined by the effect of a mutation in that gene, which causes the loss of contiguous body segments, resembling a gap in the normal body plan. Each gap gene, therefore, is necessary for the development of a section of the organism.
Defects in this gene lead to the most common form of congenital deafness in developed countries, called DFNB1 (also known as connexin 26 deafness or GJB2-related deafness). [7] One fairly common mutation is the deletion of one guanine from a string of six, resulting in a frameshift and termination of the protein at amino acid number 13. Having ...
Gap junction beta-1 protein (GJB1), also known as connexin 32 (Cx32), is a transmembrane protein that in humans is encoded by the GJB1 gene. [a] [5] Gap junction beta-1 protein is a member of the gap junction connexin family of proteins that regulates and controls the transfer of communication signals across cell membranes, primarily in the liver and peripheral nervous system. [6]
Pair-rule genes are expressed as a result of differing concentrations of gap gene proteins, which encode transcription factors controlling pair-rule gene expression. [1] [2] Pair-rule genes are defined by the effect of a mutation in that gene, which causes the loss of the normal developmental pattern in alternating segments.
In situ hybridization against mRNA of the gap genes knirps, Krüppel and giant in the Drosophila melanogaster early embryo. Panels also show how these genes are affected by the mutation brakeless (bks). Krüppel is a gap gene in Drosophila melanogaster, located on the 2R chromosome, which encodes a zinc finger C2H2 transcription factor.
Connexins are commonly named according to their molecular weights, e.g. Cx26 is the connexin protein of 26 kDa. A competing nomenclature is the gap junction protein system, where connexins are sorted by their α (GJA) and β (GJB) forms, with additional connexins grouped into the C, D and E groupings, followed by an identifying number, e.g. GJA1 corresponds to Cx43.
These G proteins acquire missense mutations that disrupt the inherent GTPase activity of the proteins. The mutant G proteins are still bound by GAPs, [16] but enhancing GTPase activity by the GAPs is meaningless when GTPase activity of the G protein itself is lost. GAP works to activate a nonfunctional hydrolytic enzyme.
Gap penalties account for the introduction of a gap - on the evolutionary model, an insertion or deletion mutation - in both nucleotide and protein sequences, and therefore the penalty values should be proportional to the expected rate of such mutations. The quality of the alignments produced therefore depends on the quality of the scoring ...