Involved in starvation response and aggregation stage of the life cycle. May be involved in fruiting body morphogenesis and spore formation. By starvation. Rapidly and transiently expressed in the first 5 min following the removal of nutrients. Expression declines after 30 min and is undetectable 2 hr after nutrient removal. Cells show no aggregation after 11.5 hr of starvation under submerged conditions in contrast to the wild-type. Cells developed on agar exhibit 2 hr delay in aggregation and the aggregation streams formed after 9 hr are larger than normal leading to over-sized mounds. No significant difference in the time of conversion of mounds to migrating slugs, but the larger slugs formed by the mutant cells often subdivide before forming normal-sized fruiting bodies with an apparently normal proportion of spores and stalk. Grp94 transcript decreases more slowly following starvation compared to rapid within 30 min decrease of it in wild-type. Significantly reduced and delayed expression of the aggregation stage adenylate cyclase acaA and cyclic AMP receptor carA genes. Both are normally expressed shortly after the initiation of differentiation upon starvation and they are necessary for chemotactic aggregation.