The ''achaete-scute'' complex (''AS-C'') is a group of four genes (''achaete'', ''scute'', ''lethal of scute'', and ''asense'') in the fruit fly ''

Drosophila melanogaster ''Drosophila melanogaster'' is a species of fly (the taxonomic order Diptera) in the family Drosophilidae. The species is often referred to as the fruit fly or lesser fruit fly, or less commonly the " vinegar fly" or "pomace fly". Starting with ...

''. These genes encode

basic helix-loop-helix BASIC (Beginners' All-purpose Symbolic Instruction Code) is a family of general-purpose, high-level programming languages designed for ease of use. The original version was created by John G. Kemeny and Thomas E. Kurtz at Dartmouth College ...

transcription factors In molecular biology, a transcription factor (TF) (or sequence-specific DNA-binding factor) is a protein that controls the rate of transcription of genetic information from DNA to messenger RNA, by binding to a specific DNA sequence. The fun ...

that have been best studied in their regulation of nervous system development. Because of their role in specifying neuroblast fate, the genes of the ''AS-C'' are called proneural genes. However, the ''AS-C'' has non-proneural functions, such as specifying muscle and gut progenitors. Homologues of ''AS-C'' in other animals, including humans and other vertebrates, have similar functions. Genes of the ''AS-C'' interact with the Notch pathway in both their proneural functions as well as their specification of gut and muscle cells.

Genetic structure

The complex is found near the tip of the X chromosome, just 3' of ''yellow'', in chromosome bands 1A6 through 1B3. It occupies around 93 kb of the genome, with all four genes oriented in the same direction.

''achaete''

The 5′-most gene of the achaete-scute complex, ''achaete'' (short form ''ac'') is a small gene of less than 1000 bp. The Achaete protein is 201

amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha ...

s long and has a relative size of 23

kDa The dalton or unified atomic mass unit (symbols: Da or u) is a non-SI unit of mass widely used in physics and chemistry. It is defined as of the mass of an unbound neutral atom of carbon-12 in its nuclear and electronic ground state and at re ...

. As with most classically described ''Drosophila'' genes, ''achaete'' is named for its mutant phenotype, which is the lack of sensory hairs (macrochaetae and microchaetae) on the back of the adult fly. Achaete functions to specify sensory hair cell fate. It functions downstream of other genes, including ''hairy'' and ''extramacrochaete'' that set up fields of cells that may express ''achaete''.

''scute''

''scute'' (short form ''sc'') is found about 25 kb 3′ of ''achaete''. It is a 1.45 kb gene encoding a 345 aa protein of 38.2 kDa.

''lethal of scute''

''lethal of scute'' (short form ''l(1)sc'') is found about 12 kb 3′ of ''scute''. It is a 1.1 kb gene encoding a 257 aa protein of 29 kDa.

''asense''

''asense'' (short form ''ase'') found 45 kb 3′ of ''l(1)sc''. It is a 2.8 kb gene encoding a 486 aa protein of 53.2 kDa.

References