The PAK enzyme family comprises six members subdivided into two groups: Group I, represented by PAK1, 2, and 3, and Group II, represented by PAK 4, 5, and 6, based on sequence and structural homology.
The transfer of the α-amino group of glutamate to pyruvate to form alanine is catalysed by alanine aminotransferases (AlaAT or AOAT; EC 2.6.1.2) which comprise four members, subdivided into two groups, in A. thaliana [ 27].
The pro-apoptotic Bcl-2 members are subdivided into 'multidomain' and 'Bcl-2 Homology (BH3)' proteins.
The 17 PARP family members can be subdivided into four subfamilies based on their domain architectures (Table 1).
The PAK family is comprised of six members and is subdivided into two groups (Groups I and II) based on sequence and structural homology.
The type II family of serine proteases includes 20 members that are subdivided into four subfamilies: matriptase, hepsin/transmembrane protease/serine (TMPRSS), HAT/differentially expressed in squamous cell carcinoma (DESC) and corin (Szabo and Bugge, 2008).
Pro-apoptotic members can be subdivided into the multidomain BH123 homologs (Bax and Bak), and the proteins of the BH3-only subfamily (Bad, Bim, Puma, Noxa, Nbk/Bik, Bmf, Bnip3, Hrk and Bid).
Bcl-2 family members can be roughly subdivided into anti- and pro-apoptotic proteins.
The superfamily of mammalian Ras like proteins comprises over 150 members that can be subdivided into five main families, namely Ras, Rho, Rab, Arf and Ran and all control rather specifically one particular facet of cell metabolism.
The proapoptotic family members instead can be subdivided into effector proteins, such as BAK and BAX, that were originally described to contain only BH1-3, and into the BH3-only proteins that share homology only in the third domain and comprise BAD, BID, BIM, BIK, PUMA, Noxa and others [32].
The Bcl-2 family is subdivided into antiapoptotic members, including Bcl-2 and Bcl-XL, and proapoptotic members, including Bax and Bak [ 16, 17].
