inner layer of spore wall

GO:0005632 · Spore · Envelope layer · Proposed

Either of the two innermost layers of the spore wall, as described in Saccharomyces. [GO:0005632]

Part of: ascospore wall (GO:0005619)

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
ascospore inner-wall mannan and beta-glucan polymers	Polysaccharide	part of	Reviewed label only (reviewed name; no accession asserted)			ESSENTIAL	Mannan- and beta-glucan-rich polysaccharide material that forms the two innermost layers of the Saccharomyces ascospore wall. `GO:0005632` GO:0005632 identifies either of the two innermost Saccharomyces spore-wall layers. `DOI:10.1128/MMBR.69.4.565-584.2005` Neiman 2005 reviews the mannan- and glucan-rich inner layers of the Saccharomyces cerevisiae ascospore wall.

Taxonomic distribution

NCBITaxon:4932 Saccharomyces cerevisiae — COMMON: Budding yeast builds inner mannan- and glucan-rich layers under the chitosan and dityrosine layers during ascospore-wall maturation; this standalone record does not assert identical inner-layer chemistry throughout ascospore-forming fungi. [DOI:10.1128/MMBR.69.4.565-584.2005]

Canonical examples

NCBITaxon:4932 Saccharomyces cerevisiae — Budding-yeast model in which the inner mannan- and beta-glucan-rich layers are deposited beneath the outer chitosan and dityrosine layers. [DOI:10.1128/EC.3.6.1464-1475.2004]

Functions

basal ascospore-wall scaffold — The inner spore-wall layers form the basal Saccharomyces ascospore wall beneath the chitosan and dityrosine outer layers during maturation.
- DOI:10.1128/EC.3.6.1464-1475.2004 Coluccio et al. 2004 analyzed the morphogenetic pathway of Saccharomyces spore-wall assembly.
- DOI:10.1128/MMBR.69.4.565-584.2005 Neiman 2005 reviews deposition of the multilaminar Saccharomyces ascospore wall after prospore-membrane closure.

Mechanism graphs

Mannan and beta-glucan polymers form the inner Saccharomyces ascospore-wall layers (ASSEMBLY)

In Saccharomyces cerevisiae, mannan- and beta-glucan-rich polysaccharide material forms the two inner ascospore-wall layers beneath the chitosan and dityrosine outer layers.

Subject	Predicate	Object	Evidence
ascospore inner-wall mannan and beta-glucan polymers	forms	inner layer of spore wall	`GO:0005632` GO:0005632 identifies either of the two innermost Saccharomyces spore-wall layers. `DOI:10.1128/MMBR.69.4.565-584.2005` Neiman 2005 reviews the inner mannan- and glucan-rich Saccharomyces ascospore-wall layers.
inner layer of spore wall	is layer of	ascospore wall	`GO:0005632` GO:0005632 defines the inner spore-wall layer as part of the Saccharomyces spore wall. `GO:0005619` GO places GO:0005632 as part of the ascospore wall.
chitosan layer of spore wall	overlies	inner layer of spore wall	`GO:0005631` GO:0005631 defines the chitosan layer as the second outermost Saccharomyces spore-wall layer. `GO:0005632` GO:0005632 defines the inner layers as the two innermost Saccharomyces spore-wall layers.
dityrosine layer of spore wall	overlies	chitosan layer of spore wall	`GO:0005630` GO:0005630 defines the dityrosine layer as the outermost Saccharomyces spore-wall layer. `GO:0005631` GO:0005631 places the chitosan layer immediately beneath the dityrosine layer.

Discussions

CURATION_TODO (OPEN): Resolve exact source-neutral groundings for the inner ascospore-wall mannan and beta-glucan polymers. GO:0005632 identifies the complete inner spore-wall layer structure, while the record's molecular component names Saccharomyces inner-wall mannan and beta-glucan polymers without mapping that mixture to exact source-neutral CHEBI identifiers.

Evidence

GO:0005632 Gene Ontology cellular-component term for the Saccharomyces inner spore-wall layer.
GO:0005619 Gene Ontology cellular-component term for the broader ascospore wall that contains the inner spore-wall layers.
GO:0005631 Gene Ontology cellular-component term for the chitosan layer outside the Saccharomyces inner spore-wall layers.
GO:0005630 Gene Ontology cellular-component term for the dityrosine layer outside the Saccharomyces chitosan layer.
DOI:10.1128/EC.3.6.1464-1475.2004 Coluccio et al. 2004, Morphogenetic pathway of spore wall assembly in Saccharomyces cerevisiae, Eukaryotic Cell.
DOI:10.1128/MMBR.69.4.565-584.2005 Neiman 2005, Ascospore Formation in the Yeast Saccharomyces cerevisiae, Microbiology and Molecular Biology Reviews.

Curation history

2026-09-23T02:55:22Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-23T02:56:26Z codex · EXPANDED_RECORD — Added ascospore-wall parthood, a reviewed-label-only inner mannan/beta-glucan polysaccharide component, Saccharomyces cerevisiae scope, a basal-wall scaffold function, GO/DOI evidence, a nonmechanistic inner-layer topology graph, and a component-grounding TODO.
2026-09-23T02:57:01Z codex · EXPANDED_EVIDENCE — Added GO:0005630 record-level evidence for the dityrosine layer node in the Saccharomyces inner-layer topology graph.

Source: data/structures/spore/inner_layer_of_spore_wall.yaml