Found in functional membrane microdomains (FMM) that may be equivalent to eukaryotic membrane rafts. FMMs are highly dynamic and increase in number as cells age. FloA and FloT function is partially redundant; double deletions have marked synthetic phenotypes (PubMed:20713508, PubMed:22753055, PubMed:25909364, PubMed:27362352). Flotillins are thought to be important factors in membrane fluidity, especially during periods of rapid growth in rich media (Probable). Whether specific proteins are associated with FMMs is controversial; in one study FloT rafts have been shown to include proteins involved in adaptation to stationary phase, while FloA-FloT rafts include proteins involved in differentation including sporulation, biofilm formation and DNA uptake competence. Another (more finely resolved) study only showed association of NfeD2 with FloT rafts of all the proteins examined (PubMed:25909364, PubMed:27362352). Aids homooligomerization of KinC and KinD but not KinB, may prevent incorrect hetero-association of the above kinases (PubMed:26297017). Simultaneous overexpression of both FloA and FloT leads to defects in cell division and differentiation, in part caused by stabilization of FtsH and its subsequent increased ability to degrade proteins. Cells make more biofilm, are about half as long, have less EzrA and more frequent Z-rings (PubMed:24222488). Involved in spatial organization of membranes, perhaps recruiting proteins (e.g. NfeD2) to specific membrane regions (Probable) (PubMed:23651456). Plays a role in phosphorylation of master regulator Spo0A, an early sporulation event (PubMed:19383680). Plays a non-redundant role with dynamin-like protein A (dynA) in membrane dynamics and cell shape (PubMed:23249255). Homooligomerizes (PubMed:25909364). Oligomerizes in very large complexes in vitro. Interacts with FloA, FtsH, FtsX, OppA, SdhA and SecY in detergent-resistant membrane (DRM) fractions (PubMed:23651456). Interacts with FtsH at midcell (Probable). Interacts with FloA (PubMed:25909364). Interacts in vivo with KinC, FloA, FtsH and ResE (PubMed:26297017). Interacts with ResE, colocalizes with ResE in FloT-only membrane rafts (PubMed:25909364). Another study shows nearly complete colocalization with NfeD2, but only minor colocalization with FtsH or KinC (PubMed:27362352). Tethered to the membrane by a hairpin loop that inserts into the cell membrane (PubMed:25635948). A few foci are seen on the cell membrane during exponential growth, more are seen as cells enter stationary phase. Restricted to the mother cell during sporulation. Foci form a spiral track on the cell membrane and move in the cell. Associated with high bouyancy, cardiolipin- and phosphatidylglycerol-rich membrane fractions, association is not obligatory (PubMed:19383680). Present in detergent-resistant membrane (DRM) fractions, approximately 6 dynamic foci per cell; colocalizes with KinC and sometimes with FloA in DRMs. Foci are lost when cells are treated with squalene synthase inhibitor zaragozic acid (PubMed:20713508). Found in discrete, highly mobile foci, often colocalizes with NfeD2 but rarely with FloA (PubMed:22753055). Forms discrete foci on the cell membrane, about 20% of foci are at the septal site. At the septa colocalizes with FloA and FtsH (PubMed:22882210, PubMed:23249255). Colocalizes with FtsX, OppA, SdhA and SecY in DRMs (PubMed:23651456). Careful analysis gives an average of 13 FloA and 6 FloT foci per cell; FloA foci are smaller that FloT foci (PubMed:25909364). Another study shows FloA and FloT foci are similar in size, forming membrane assemblies of 85-110 nm. FloA are more mobile than FloT foci and they do not overlap. This study found no evidence of colocalization of FloA with FloT, and nearly complete colocalization of FloT with NfeD2 (PubMed:27362352). Transcription starts during stationary phase. Few foci are seen in exponential phase cells; the number of foci increases as cells enter stationary phase (at protein level) (PubMed:19383680, PubMed:23651456, PubMed:22753055). Few foci are seen on rich media, when cells are grown in minimal medium more foci are seen (at protein level) (PubMed:22753055). Expressed at low levels in rich media during exponential growth, more highly expressed in stationary phase on sporulation/biofilm-inducing media, activated by spo0A probably via AbrB (at protein level). Surfactin induces expression via spo0A (PubMed:25909364). A hairpin loop (about residues 4-24) tethers the protein in the inner membrane. The isolated PHB domain (also called SPFH) oligomerizes, but does not bind lipids (PubMed:25635948). The C-terminal 24 residues are not required for correct localization, but the last 300 residues are required (PubMed:22753055). The C-terminus determines the oligomerization state of the protein; there are few large foci for FloT. Swapping with the C-terminus of FloA leads to many smaller foci (PubMed:25909364). Delay in sporulation onset, 65% reduction in sporulation efficiency (PubMed:19383680, PubMed:22882210). No effect on KinC activity, a double floT-floA deletion decreases the number of proteins in the DRM, blocks the ability of KinC to stimulate biofilm formation (PubMed:20713508). Single floT deletion has defective motility, loss of NfeD2 localization, no change in FloA localization. Double floA-floT mutants have marked defects in cell morphology, motility, and transformation efficiency (PubMed:22753055). Double floA-floT deletion makes no biofilm, has greatly reduced FtsH, sporulates less than either single mutant (PubMed:22882210). Double dynA-floT deletions are highly elongated, filamentous and have strong defects in cell shape; cells grow very slowly with an extended lag phase (PubMed:23249255). Single mutation has a decrease in membrane fluidity and 35% decrease in protein secretion, a double floT-floA deletion has a stronger decrease in membrane fluidity and the same decrease in protein secretion (PubMed:23651456). Double dynA-floT deletion strains are less motile than single floT deletions (PubMed:26842743). Double floA-floT deletion has reduced oligomerization of KinC (PubMed:26297017). Double floA-floT deletion cells are somewhat elongated, the site of cell wall synthesis is affected, increasing at division septa. The speed of MreB movement around the cell is significantly decreased in rich medium in the floA-floT mutant (PubMed:32662773). Belongs to the band 7/mec-2 family. Flotillin subfamily.