TCDB is operated by the Saier Lab Bioinformatics Group

9.B.29 The small 4-5 TMS Putative Permease (4-5PP) Family

The 4-5PP family consists of proteins from Spirochaetes (Leptospira (subfamily 1)) and many potentially distant homologues in other bacteria (subfamilies 2 - 4) as well as archaea (subfamily 5).  They have 200 - 270 aas with 4 - 5 TMSs. Some of them are encoded adjacent to genes coding for membrane fusion proteins (MFPs; 8.A.1) and outer menbrane factors (OMFs; 1.B.17) implying they are effulx systems. These proteins may be distantly related to but members of the ABC superfamily (3.A.1). 

References associated with 9.B.29 family:

Drew, D., D. Sjöstrand, J. Nilsson, T. Urbig, C.N. Chin, J.W. de Gier, and G. von Heijne. (2002). Rapid topology mapping of Escherichia coli inner-membrane proteins by prediction and PhoA/GFP fusion analysis. Proc. Natl. Acad. Sci. USA 99: 2690-2695. 11867724