9.B.106 The Pock Size-determining Protein (PSDP) Family
The pock size-determining protein, SpdB, is encoded on plasmid pSN22 (Kataoka et al., 1991a). It may enhance efficiency of plasmid transfer (Kataoka et al., 1991b). It is under TraR control and has 325 aas and 4 N-terminal TMSs. Four SpdB proteins (SpdB1-SpdB4) have been idntified (Kataoka et al., 1994). The C-terminal hydrophilic domain is an Ala/Glu-rich domain that is similar to domains in other proteins such as TolA of E. coli (TC# 1.A.30.2.2). The SpdA (TC# 9.B.106.2.1) and SpdB proteins may function together. It appears that families 9.B.54, 9.B.106, and 9.B.148, all containing 4 TMS members, may be homologous.