Connects cell membrane constituents to the actin cytoskeleton. May promote orthogonal branching of actin filaments and links actin filaments to membrane glycoproteins. Anchors various transmembrane proteins to the actin cytoskeleton (By similarity). Homodimer. Interacts with FLNA, FLNC, INPPL1, ITGB1A, ITGB1D, ITGB3, ITGB6, MYOT, MYOZ1, PSEN1 and PSEN2. Interacts with MICALL2 (By similarity). Interacts with RFLNA and RFLNB (By similarity). Interacts with HTLV-I viral p13 protein. Interacts with ASB2; the interaction targets FLNB for proteasomal degradation (By similarity). ISGylation prevents ability to interact with the upstream activators of the JNK cascade and inhibits IFNA-induced JNK signaling. Ubiquitination by a SCF-like complex containing ASB2 leads to proteasomal degradation which promotes muscle differentiation. Belongs to the filamin family.