The present invention relates to a new family of structurally and functionally related nucleic acids and proteins, designed the CATERPILLER family, which is characterized by landmark structural motifs including a nucleotide binding domain and leucine-rich repeat domains. The nut has at least a cutting through itself. The upper elongated portion is constructed of a wood material, and the lower elongated portion is constructed of a non-wood material. The base is received in the slot structure and extends into the interior space so that a portion of the base engages the fuel injector to limit movement thereof both axially and radially with respect to the receiving cup, with the wall being disposed adjacent to a portion of the outer wall of the receiving cup.