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Mating hormone A-factor 1&2 The polypeptides encoded by the MFa1 and MFa2 genes are precursors of 36 and 38 amino acids, respectively. These mating pheromones secreted by S. cerevisiae a-cells, exhibit a single amino acid residue difference (the MFa1 gene product contains a valine instead of the leucine coded for by MFa2 at position 6 of the mature a-factor). The most significant feature of the primary a-factor gene products is the presence of a specific C-terminal motif, found in all known farnesylated proteins, representing a signal for modification of polypeptides with an isoprenoid group. In the case of both a-factor precursors, this specific sequence of amino acids is -CVIA. However, the general motif is referred to as a CAAX box, since the consensus sequence of amino acids present at the C terminus of isoprenylated proteins consists of an invariable cysteine (C) residue followed by two aliphatic (A) amino acids and ending in a carboxyl-terminal residue of almost any (X) type The specific CAAX sequence has also been shown to target the peptide for either farnesylation or geranylgeranylation. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",