Part of - deprecated
See http://obofoundry.org/ro#part_of
In GO (and in RO), A part_of B means that every A is part_of some B.
For example: nucleus part_of cell
Contrast with has_part
Annotation Examples:
Enhancing Cell Component Annotations
Localization
Specifying that a gene product is located in a cellular component of a specific cell type
Examples of these usages of occurs_in can be found on the documentation page for Column_16:_Cell_Type
Enhancing Molecular Function and Biological Process Annotations
Specifying the developmental stage at which a process occurs
We can use a developmental stage ontology and the part_of relation. part_of is used because both the process/function and the developmental stages are things with temporal parts (they are occurrents in bfo-speak).
For example, apoptosis during Segmentation:1-4 somites in zebrafish
col5: GO:0006915 col16: part_of(ZFS:0000023)