The ASAP1 locus spans 391,75 kb, on the minus strand of chromosome 8 from 131456099 to 131064346.

Transcription produces 16 different mRNAs, 12 alternatively spliced variants and 4 unspliced forms.
There are 9 probable alternative promotors, 6 non overlapping alternative last exons and 5 validated alternative polyadenylation sites. The mRNAs appear to differ by truncation of the 5 end, truncation of the 3 end, presence or absence of 15 cassette exons, overlapping exons with different boundaries (NCBI).

Epithelial cells, fibroblasts, macrophages, brain (for references see above), and endothelial cells (Hashimoto et al., 2011). Not determined with the other types of cells.

Intracellular tubulovesicular structures and vesicles, plasma membrane protrusions and leading edges, and invadopodia/podosome structures (Hashimoto et al., 2004; Hashimoto et al., 2005; Onodera et al., 2005).

ASAP1 has an ArfGAP zinc-finger domain and exhibits phosphatidylinositol 4,5-bisphosphate-dependent GAP activities for Arf1 and Arf5 but 10²- to 10³-fold less activity for Arf6 (Brown et al., 1998; Andreev et al., 1999). ASAP1 was shown to enhance cell motility, and this activity was proposed to be mediated by its GAP activity towards Arf1 (Furman et al., 2002). ASAP1 was also shown to associate with focal adhesion kinase (FAK) and contribute to focal adhesion assembly (Liu et al., 2002). Hashimoto et al. (2004 and 2005) have shown that AMAP1 and AMAP2 have the ability to bind stably with GTP-Arf6, but not GDP-Arf6 or other GTP-/GDP-Arf isoforms, in vitro and in vivo. Through this binding, AMAP1 and AMAP2 appear to function as downstream effectors for GTP-Arf6 (Hashimoto et al., 2004; Hashimoto et al., 2005; Onodera et al., 2005). AMAP1 binds to paxillin and cortactin, which are essential components of the invadopodia of MDA-MB-231 breast cancer cells, and acts to recruit these proteins to the sites of Arf6 activation to form invadopodia (Onodera et al., 2005). AMAP1 is hence essential for invasion and metastasis of some breast cancer cells, while AMAP2 is not a component of invadopodia (Onodera et al., 2005; Hashimoto et al., 2006; Nam et al., 2007; Morishige et al., 2008; Sabe et al., 2009). AMAP1 appears to be a useful diagnostic marker as well as therapeutic target of different types of human cancers (see below).