inner membrane pellicle complex

GO:0070258 · Membrane organelle · Membrane bounded organelle · Proposed

An apicomplexan double-membrane pellicle structure formed by flattened vesicles beneath the plasma membrane. [GO:0070258]

Synonyms: inner membrane complex

UniProt location names: UniProt Consortium, CC BY 4.0. Reference label and route sources.

Components

Component	Type	Part of / acts on	Grounding	Genes	Stoichiometry	Essential	Role
flattened IMC alveolar membranes	Lipid	part of	Reviewed label only (reviewed name; no accession asserted)			ESSENTIAL	Flattened double-membrane cisternae that lie beneath the parasite plasma membrane and form the membranous part of the apicomplexan pellicle. `DOI:10.3389/fcimb.2020.611801` Ferreira et al. 2021 review the Plasmodium IMC as a double membrane organelle beneath the parasite plasma membrane. `DOI:10.1242/jcs.099002` Dearnley et al. 2012 resolved flattened subpellicular membrane compartments beneath the Plasmodium falciparum gametocyte plasma membrane.
alveolin subpellicular network	Protein	part of	Reviewed label only (reviewed name; no accession asserted)			UNKNOWN	Peripheral membrane proteins that form a cytoskeletal network on the cytoplasmic face of the IMC. `DOI:10.3389/fcimb.2020.611801` Ferreira et al. 2021 review alveolins as Alveolata-specific IMC proteins that form a subpellicular network at the IMC cytoplasmic face. `DOI:10.1093/molbev/mss081` Kono et al. 2012 analysed Plasmodium alveolin proteins in inner-membrane-complex architecture across asexual and sexual malaria-parasite stages.

Taxonomic distribution

NCBITaxon:5794 Apicomplexa — COMMON: The inner membrane complex is a pellicle organelle of apicomplexan parasites, with stage-specific architecture in Plasmodium and lineage-specific functional differences. [DOI:10.2741/4157]

Canonical examples

NCBITaxon:5833 Plasmodium falciparum — Human malaria parasite in which the IMC has been studied through asexual and sexual stages, including gametocyte subpellicular-membrane assembly. [DOI:10.1093/molbev/mss081]

Functions

pellicle shape support — The IMC and associated subpellicular proteins stabilize parasite morphology as part of the apicomplexan pellicle.
- DOI:10.3389/fcimb.2020.611801 Ferreira et al. 2021 review the Plasmodium IMC as a compartment that confers cell stability and shape.
daughter-cell scaffolding — The IMC provides a scaffold for apicomplexan daughter-cell formation during parasite replication.
- DOI:10.1093/molbev/mss081 Kono et al. 2012 followed IMC architecture during asexual and sexual Plasmodium development.
- DOI:10.3389/fcimb.2020.611801 Ferreira et al. 2021 review the IMC as an important scaffold during daughter-cell formation in Plasmodium spp.
glideosome anchoring for motility — The apicomplexan IMC anchors gliding-motility machinery used for parasite movement and host-cell invasion.
- DOI:10.3389/fcimb.2020.611801 Ferreira et al. 2021 review the IMC as the anchor for the actin-myosin glideosome that powers gliding motility and invasion.

Mechanism graphs

IMC membranes and alveolins scaffold the pellicle (FUNCTION)

Flattened IMC alveolar membranes and the alveolin subpellicular network form a double-membrane organelle beneath the plasma membrane that supports parasite shape and gliding-motility machinery.

Subject	Predicate	Object	Evidence
flattened IMC alveolar membranes	form	inner membrane pellicle complex	`DOI:10.3389/fcimb.2020.611801` Ferreira et al. 2021 review the Plasmodium IMC as a double membrane organelle.
alveolin subpellicular network	localizes to	inner membrane pellicle complex	`DOI:10.3389/fcimb.2020.611801` Ferreira et al. 2021 review alveolins as subpellicular IMC proteins.
inner membrane pellicle complex	is part of	apicomplexan parasite pellicle	`DOI:10.3389/fcimb.2020.611801` Ferreira et al. 2021 review the relationship between the IMC and parasite pellicle.
inner membrane pellicle complex	supports	stable parasite morphology	`DOI:10.3389/fcimb.2020.611801` Ferreira et al. 2021 review IMC roles in cell stability and shape.
inner membrane pellicle complex	anchors	actin-myosin glideosome	`DOI:10.3389/fcimb.2020.611801` Ferreira et al. 2021 review glideosome anchoring at the IMC.
actin-myosin glideosome	supports	host-cell invasion	`DOI:10.3389/fcimb.2020.611801` Ferreira et al. 2021 review gliding motility and invasion roles for IMC-anchored actin-myosin machinery.

Discussions

CURATION_TODO (OPEN): Resolve exact source-neutral groundings for alveolins, GAPM proteins, inner-membrane-complex subcompartment proteins, and glideosome-associated IMC membrane proteins. Plasmodium and Toxoplasma studies define many IMC proteins and several subfamilies, but this first record uses only a broad alveolin protein cohort to avoid overclaiming exact protein-family CURIEs.

Evidence

DOI:10.3389/fcimb.2020.611801 Ferreira et al. 2021, The Dynamic Roles of the Inner Membrane Complex in the Multiple Stages of the Malaria Parasite, Frontiers in Cellular and Infection Microbiology.
DOI:10.2741/4157 Kono et al. 2013, The apicomplexan inner membrane complex, Frontiers in Bioscience.
DOI:10.1093/molbev/mss081 Kono et al. 2012, Evolution and architecture of the inner membrane complex in asexual and sexual stages of the malaria parasite, Molecular Biology and Evolution.
DOI:10.1242/jcs.099002 Dearnley et al. 2012, Origin, composition, organization and function of the inner membrane complex of Plasmodium falciparum gametocytes, Journal of Cell Science.

Curation history

2026-09-10T12:31:27Z claude · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-10T12:32:11Z claude · EXPANDED_RECORD — Added IMC synonymy, intracellular membrane-bounded-organelle parentage, flattened alveolar membrane and alveolin-network components, Apicomplexa and Plasmodium falciparum scope, pellicle-shape, daughter-cell scaffold and glideosome-anchoring functions, a nonmechanistic IMC scaffold graph, and a grounding TODO for exact IMC protein cohorts.
2026-09-10T12:42:24Z claude · ADDRESS_REVIEW — Addressed PR #365 review issues #366 and #367 by citing the apicomplexan IMC review for Apicomplexa-wide taxonomic scope and by retyping the IMC shape-stability graph node as a stable parasite-morphology state.

Source: data/structures/membrane_organelle/inner_membrane_pellicle_complex.yaml