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 many 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.106, and 9.B.148, all containing 4 TMS members, may be homologous to holins of TC family 1.E.72.
This family belongs to the N-terminal 4-TMS DMT-like Protein (N4D) Superfamily.
References:
Das, S. and E. Knust. (2017). Stardust, the Janus-faced partner of Crumbs. J. Cell Biol. 216: 1219-1221.
Kataoka, M., T. Seki, and T. Yoshida. (1991). Five genes involved in self-transmission of pSN22, a Streptomyces plasmid. J. Bacteriol. 173: 4220-4228.
Kataoka, M., T. Seki, and T. Yoshida. (1991). Regulation and function of the Streptomyces plasmid pSN22 genes involved in pock formation and inviability. J. Bacteriol. 173: 7975-7981.
Kataoka, M., Y.M. Kiyose, Y. Michisuji, T. Horiguchi, T. Seki, and T. Yoshida. (1994). Complete nucleotide sequence of the Streptomyces nigrifaciens plasmid, pSN22: genetic organization and correlation with genetic properties. Plasmid 32: 55-69.
Lin, H., W. Du, Y. Yang, K.S. Schumaker, and Y. Guo. (2014). A calcium-independent activation of the Arabidopsis SOS2-like protein kinase24 by its interacting SOS3-like calcium binding protein1. Plant Physiol. 164: 2197-2206.
Mendes, M.V., J.F. Aparicio, and J.F. Martín. (2000). Complete nucleotide sequence and characterization of pSNA1 from pimaricin-producing Streptomyces natalensis that replicates by a rolling circle mechanism. Plasmid 43: 159-165.
Examples:
TC#	Name	Organismal Type	Example
9.B.106.1.1	The pock size-determining protein, SpdB	Bacteria	*SpdB of Streptomyces coelicolor* (Q9F2T7)**

9.B.106.1.2	gp25 phage protein	Actinobacterial Phage	*gp25 of Streptomyces* phage phiBT1 (Q858X7)**

9.B.106.1.3	Putative plasmid transfer protein, SpdB2. Residues 191-443 give e^-17 with TolA (2.C.1.2.1) residues 59-315, both being A+E-rich domains. Many other proteins in TCDB also have this hydrophilic domain.	Actinobacteria	*SpdB2 of Streptomyces rochei* (F2Z8Q7)**

9.B.106.1.5	Uncharacterized protein of 205 aas and 4 TMSs		UP of Saccharothrix espanaensis

9.B.106.1.7	Uncharacterized protein of 442 aas and 3 or 4 N-terminal TMSs.		UP of Streptomyces albulus

9.B.106.1.8	DUF2637 domain-containing protein of 327 aas and 4 N-terminal TMSs.		*DUF2637 protein of Kineococcus* sp. T90**

9.B.106.1.9	DUF2637 domain-containing protein of 273 aas and 4 N-terminal TMSs.		DUF2637 protein of Actinocorallia herbida

Examples:
TC#	Name	Organismal Type	Example
Examples:
TC#	Name	Organismal Type	Example
Examples:
TC#	Name	Organismal Type	Example