CHMP4B Antibody [P12D13] | Primary Antibodies

Application: Reactivity: Human, Mouse, Rat

Usage Information

Dilution
WB1:1000 IP1:50

Application
WB, IP

Reactivity
Human, Mouse, Rat

Source
Rabbit Monoclonal Antibody

Storage Buffer
PBS, pH 7.2+50% Glycerol+0.05% BSA+0.01% NaN3

Storage (from the date of receipt)
-20°C (avoid freeze-thaw cycles), 2 years

Predicted MW
19 kDa

Datasheet & SDS

Biological Description

Specificity
CHMP4B Antibody [P12D13] detects endogenous levels of total CHMP4B protein.

Clone
P12D13

Synonym(s)
C20orf178; Charged multivesicular body protein 4b; CHM4B; CHMP4A; CHMP4B; CTPP3; CTRCT31; dJ553F4.4; hSnf7-2; hVps32-2; SHAX1; SNF7; Snf7 homologue associated with Alix 1; SNF7-2; Vps32-2; VPS32B

Background
CHMP4B (charged multivesicular body protein 4B) represents a core component of the endosomal sorting complex required for transport-III (ESCRT-III), which executes membrane scission events across diverse cellular processes, including multivesicular body formation, cytokinesis, viral budding, nuclear envelope sealing, and plasma membrane repair. CHMP4B belongs to the highly conserved ESCRT-III protein family and functions as the human ortholog of yeast Snf7, sharing a characteristic molecular architecture comprising a positively charged N-terminal region organized into two helices forming a 70-angstrom hairpin essential for membrane binding and oligomerization, central helices forming an asymmetric antiparallel four-helix bundle, and a negatively charged C-terminal autoinhibitory region containing MIT-interacting motifs for VPS4 ATPase recruitment. The protein exists predominantly in a folded, closed conformation in the cytoplasm, with the C-terminal acidic region intramolecularly binding the N-terminal hairpin to maintain autoinhibition until activation signals trigger conformational changes releasing this inhibition and exposing membrane interaction sites. CHMP4B becomes recruited to target membranes through distinct upstream adaptors depending on cellular context—during multivesicular body biogenesis, ESCRT-II mediates CHMP4B activation through interaction with CHMP6 (Vps20), while during cytokinesis the adaptor protein CEP55 recruits ESCRT-I and ALIX to the midbody, where ALIX directly activates CHMP4B by binding its C-terminal autoinhibitory region, and during HIV-1 budding, viral Gag proteins hijack ALIX and ESCRT-I to plasma membrane budding sites, initiating CHMP4B assembly. Upon activation, CHMP4B polymerizes into membrane-attached filaments that assemble into circular scaffolds, helical structures, or extended polymers depending on the biological context, with these filaments promoting or stabilizing negative membrane curvature essential for outward budding and membrane neck constriction. CHMP4B filaments organize into two distinct pools during cytokinesis—initial assembly occurs in cortical rings located on either side of the midbody center overlapping with ESCRT-I localization, then immediately before abscission CHMP4B acutely redistributes to secondary constriction sites approximately one micrometer from the midbody where it forms puncta that correlate spatially and temporally with microtubule narrowing and membrane scission. The protein nucleates ESCRT-III assembly by homo-oligomerizing into extended Snf7/CHMP4 polymers that become capped by CHMP3 (Vps24) followed by CHMP2 (Vps2) recruitment, establishing an ordered assembly pathway where CHMP4B represents the predominant ESCRT-III component dictating filament size and stoichiometry. CHMP4B filaments preferentially bind flat membranes or positively curved membrane tubes, deforming membrane necks through progressive constriction as filaments form narrowing spirals that reduce neck diameter below critical thresholds favoring spontaneous membrane fission. The AAA-ATPase VPS4 becomes recruited to CHMP4B filaments through direct MIT domain interactions with C-terminal MIM motifs, assembling into active dodecameric complexes that disassemble CHMP4B polymers by translocating subunits through the central VPS4 pore while consuming ATP, resetting CHMP4B to its autoinhibited cytoplasmic state for subsequent rounds of membrane scission. CC2D1A functions as a negative regulator of CHMP4B activity by binding the N-terminal helical hairpin with nanomolar affinity forming a one-to-one complex, with this interaction inhibiting CHMP4B polymerization and representing a regulatory checkpoint controlling ESCRT-III filament formation. CHMP4B coordinates cytokinetic abscission by recruiting the microtubule-severing enzyme spastin through interactions with the ESCRT-III protein CHMP1B, coupling membrane scission with microtubule severing to enable complete daughter cell separation. The protein proves essential for exosomal release of cargo proteins including syndecan-binding protein, CD63, and syndecan through mediating intraluminal vesicle formation within multivesicular bodies that ultimately fuse with the plasma membrane releasing exosomes. CHMP4B collaborates with spastin to promote nuclear envelope sealing and mitotic spindle disassembly during late anaphase, extending its function beyond classical membrane scission to nuclear envelope dynamics. The protein localizes to primary cilia and maintains ciliary structural integrity, with CHMP4B depletion interfering with normal cilia formation and function representing a role distinct from endosomal sorting. CHMP4B participates in plasma membrane repair during regulated necrosis and necroptosis by becoming recruited to membrane disruption sites where ESCRT-III assembly sustains membrane integrity enabling continued cell signaling and cytokine secretion despite ongoing necrotic processes. HIV-1 and other lentiviruses exploit CHMP4B for viral particle release by directing CHMP4B assembly at budding sites through interactions with the viral accessory protein p6 mediated by ALIX, with CHMP4B forming ring-like striations in membrane necks connecting budding virions that become severed upon VPS4-mediated ESCRT-III disassembly. Dominant-negative C-terminal truncated CHMP4B mutants lacking autoinhibitory regions constitutively polymerize and potently inhibit HIV-1 budding, multivesicular body formation, and cytokinetic abscission by forming hyperstable filaments resistant to VPS4 disassembly. CHMP4B exhibits elevated expression in hepatocellular carcinoma correlating with increased proliferation and doxorubicin resistance, while increased CHMP4B levels associate with neuronal apoptosis following intracerebral hemorrhage, positioning CHMP4B expression as a potential prognostic marker and therapeutic target.

Background

CHMP4B (charged multivesicular body protein 4B) represents a core component of the endosomal sorting complex required for transport-III (ESCRT-III), which executes membrane scission events across diverse cellular processes, including multivesicular body formation, cytokinesis, viral budding, nuclear envelope sealing, and plasma membrane repair. CHMP4B belongs to the highly conserved ESCRT-III protein family and functions as the human ortholog of yeast Snf7, sharing a characteristic molecular architecture comprising a positively charged N-terminal region organized into two helices forming a 70-angstrom hairpin essential for membrane binding and oligomerization, central helices forming an asymmetric antiparallel four-helix bundle, and a negatively charged C-terminal autoinhibitory region containing MIT-interacting motifs for VPS4 ATPase recruitment. The protein exists predominantly in a folded, closed conformation in the cytoplasm, with the C-terminal acidic region intramolecularly binding the N-terminal hairpin to maintain autoinhibition until activation signals trigger conformational changes releasing this inhibition and exposing membrane interaction sites. CHMP4B becomes recruited to target membranes through distinct upstream adaptors depending on cellular context—during multivesicular body biogenesis, ESCRT-II mediates CHMP4B activation through interaction with CHMP6 (Vps20), while during cytokinesis the adaptor protein CEP55 recruits ESCRT-I and ALIX to the midbody, where ALIX directly activates CHMP4B by binding its C-terminal autoinhibitory region, and during HIV-1 budding, viral Gag proteins hijack ALIX and ESCRT-I to plasma membrane budding sites, initiating CHMP4B assembly. Upon activation, CHMP4B polymerizes into membrane-attached filaments that assemble into circular scaffolds, helical structures, or extended polymers depending on the biological context, with these filaments promoting or stabilizing negative membrane curvature essential for outward budding and membrane neck constriction. CHMP4B filaments organize into two distinct pools during cytokinesis—initial assembly occurs in cortical rings located on either side of the midbody center overlapping with ESCRT-I localization, then immediately before abscission CHMP4B acutely redistributes to secondary constriction sites approximately one micrometer from the midbody where it forms puncta that correlate spatially and temporally with microtubule narrowing and membrane scission. The protein nucleates ESCRT-III assembly by homo-oligomerizing into extended Snf7/CHMP4 polymers that become capped by CHMP3 (Vps24) followed by CHMP2 (Vps2) recruitment, establishing an ordered assembly pathway where CHMP4B represents the predominant ESCRT-III component dictating filament size and stoichiometry. CHMP4B filaments preferentially bind flat membranes or positively curved membrane tubes, deforming membrane necks through progressive constriction as filaments form narrowing spirals that reduce neck diameter below critical thresholds favoring spontaneous membrane fission. The AAA-ATPase VPS4 becomes recruited to CHMP4B filaments through direct MIT domain interactions with C-terminal MIM motifs, assembling into active dodecameric complexes that disassemble CHMP4B polymers by translocating subunits through the central VPS4 pore while consuming ATP, resetting CHMP4B to its autoinhibited cytoplasmic state for subsequent rounds of membrane scission. CC2D1A functions as a negative regulator of CHMP4B activity by binding the N-terminal helical hairpin with nanomolar affinity forming a one-to-one complex, with this interaction inhibiting CHMP4B polymerization and representing a regulatory checkpoint controlling ESCRT-III filament formation. CHMP4B coordinates cytokinetic abscission by recruiting the microtubule-severing enzyme spastin through interactions with the ESCRT-III protein CHMP1B, coupling membrane scission with microtubule severing to enable complete daughter cell separation. The protein proves essential for exosomal release of cargo proteins including syndecan-binding protein, CD63, and syndecan through mediating intraluminal vesicle formation within multivesicular bodies that ultimately fuse with the plasma membrane releasing exosomes. CHMP4B collaborates with spastin to promote nuclear envelope sealing and mitotic spindle disassembly during late anaphase, extending its function beyond classical membrane scission to nuclear envelope dynamics. The protein localizes to primary cilia and maintains ciliary structural integrity, with CHMP4B depletion interfering with normal cilia formation and function representing a role distinct from endosomal sorting. CHMP4B participates in plasma membrane repair during regulated necrosis and necroptosis by becoming recruited to membrane disruption sites where ESCRT-III assembly sustains membrane integrity enabling continued cell signaling and cytokine secretion despite ongoing necrotic processes. HIV-1 and other lentiviruses exploit CHMP4B for viral particle release by directing CHMP4B assembly at budding sites through interactions with the viral accessory protein p6 mediated by ALIX, with CHMP4B forming ring-like striations in membrane necks connecting budding virions that become severed upon VPS4-mediated ESCRT-III disassembly. Dominant-negative C-terminal truncated CHMP4B mutants lacking autoinhibitory regions constitutively polymerize and potently inhibit HIV-1 budding, multivesicular body formation, and cytokinetic abscission by forming hyperstable filaments resistant to VPS4 disassembly. CHMP4B exhibits elevated expression in hepatocellular carcinoma correlating with increased proliferation and doxorubicin resistance, while increased CHMP4B levels associate with neuronal apoptosis following intracerebral hemorrhage, positioning CHMP4B expression as a potential prognostic marker and therapeutic target.

References
https://pubmed.ncbi.nlm.nih.gov/21924267/ https://pubmed.ncbi.nlm.nih.gov/21383202/

Protein Size (kDa)	PVDF Transfer Membrane Pore Size (μm)
< 10	0.22
10-20	0.22
20-30	0.45
30-45	0.45
45-70	0.45
80-100	0.45
100-140	0.45
> 140	0.45

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Protein Size (kDa)	Separating Gel Percentage
4-40	20%
12-45	15%
10-70	12.5%
15-100	10%
25-100	8%
60-210	5%