Disease relevance of MAP1A

• In this article, we have described the structure and distribution of the various variants of the microtubule-associated proteins (MAPs), tau, MAP2, MAP1A, and MAP1B, that are expressed in the dorsal root ganglion (DRG) and spinal cord during development and regeneration [1].
• We have examined the accumulation of MAP1A in retinoic acid induced P19 embryonal carcinoma (EC) neurons [2].
• This indicates that at least some of the observed polymorphisms are functionally important and that the hearing loss in C57BL/6J-tub/tub (B6-tub/tub) mice may be caused by impaired protein interactions involving MTAP1A [3].
• Analysis of microtubule-associated protein 1a gene in hereditary spastic paraplegia [4].

High impact information on MAP1A

• Widespread cellular distribution of MAP-1A (microtubule-associated protein 1A) in the mitotic spindle and on interphase microtubules [5].
• Anti-MAP 1A consistently labeled mitotic spindles and stained cytoplasmic fibers during interphase in most of the cultures [5].
• In the present study, we sought to determine the cellular and subcellular distribution of MAP 1A in commonly used cultured cell systems [5].
• The anti-MAP 1A stained microtubules in a punctate manner, raising the possibility that MAP 1A is located along microtubules at discrete foci that might represent sites of interaction between microtubules and other organelles [5].
• C19ORF5 is a sequence homologue of microtubule-associated proteins MAP1A/MAP1B of unknown function, except for its association with mitochondria-associated proteins and the paclitaxel-like microtubule stabilizer and candidate tumor suppressor RASSF1A [6].

Biological context of MAP1A

• These results suggest that RFX1 and 3 are pivotal factors in down-regulation of the MAP1A 5' promoter in non-neuronal cells [7].
• Further investigation of other areas of MAP1A revealed a protein domain, capable of autonomously binding to microtubules, which bears no homology to any previously described microtubule-binding sequence [8].
• The gene of this cDNA was assigned to human chromosome 15 that has a syntenic region of mouse chromosome 2, where the mouse MAP1A gene has been assigned [9].
• The exon/intron organization underlying the alternative transcripts and the N-terminal amino acid sequence of the putative truncated MAP1B isoforms resemble those of MAP1A, providing further evidence for an evolutionary relationship [10].
• Mammalian genomes usually contain three family members, MAP1A, MAP1B and a shorter, more recently identified gene called MAP1S [11].

Anatomical context of MAP1A

• Microtubule-associated protein MAP1A is expressed abundantly in mature neurons and is necessary for maintenance of neuronal morphology and localization of some molecules in association with the microtubule-based cytoskeleton [7].
• When the MAP1A microtubule-binding domain was co-expressed in cultured cell lines together with MAP2c, the MAP1A microtubule-binding domain was able to bind to the MAP2c-induced microtubule bundles [8].
• Less is known about MAP1A, but it is also enriched in dendrites at input locations, including PSDs where MAP1A associates with channel complexes and the calcium sensor caldendrin [12].
• Microtubule-associated proteins 1A (MAP1A) and MAP1B are abundant neuronal MAPs thought to be involved in neurite formation and stabilization [13].
• An increase in MAP1A immunoreactivity was evident in the perikarya of the dentate gyrus at 30 min postictal, whereas MAP2 immunoreactivity decreased [14].

Associations of MAP1A with chemical compounds

• Evidence that estramustine binds MAP-1A to inhibit type IV collagenase secretion [15].
• A decline of P-Cr, ATP, and GTP levels without change in %ATP, AMP, or purine bodies occurred after reperfusion for 3 days, coinciding with the development of immunohistochemical damage by the immunoreaction for microtubule-associated protein 1A [16].

Physical interactions of MAP1A

• Exchange protein directly activated by cAMP (EPAC) interacts with the light chain (LC) 2 of MAP1A [17].
• The guanylate kinase domain of the MAGUK PSD-95 binds dynamically to a conserved motif in MAP1a [18].

Other interactions of MAP1A

• Role for RFX transcription factors in non-neuronal cell-specific inactivation of the microtubule-associated protein MAP1A promoter [7].
• By comparisons of human MAP1B with the sequence databases, we have identified a MAP1B-related gene that is probably the human homologue of rat MAP1A [19].
• The amino acid sequence of VCY2IP-1 shows 59.3% and 41.9% homology to two human microtubule-associated proteins (MAPs), MAP1B and MAP1A, respectively [20].
• We determine the consensus GK-binding sequence in MAP1a and demonstrate that PSD-95 can use a similar interaction mode to bind diverse protein partners [18].
• We investigated the disintegration of microtubules using immunoelectron microscopy for alpha-tubulin and microtubule-associated protein 1A and 2 (MAP1A and 2) [21].

Analytical, diagnostic and therapeutic context of MAP1A

• MAP1B heavy chain (HC) and light chain (LC1), as well as the light chain of MAP1A (LC2), were prepared in purified form for use as standards and/or immunogens for generation of antibodies for immunoblotting [22].
• Using a solid-phase immunoassay we show that MAP1A binds in a dose-dependent manner to both G-actin and F-actin [23].
• Addition of MAP1A to F-actin causes gelation of F-actin and SDS-PAGE analysis shows that MAP1A co-sediments with the gelled network, under conditions where F-actin alone does not pellet [23].
• Western blotting and ELISA showed that MAP1A protein levels increased during differentiation [2].
• By immunofluorescent confocal microscopy, MAP1A was detected in the mitotic spindle of undifferentiated cells but was not evident in association with the interphase microtubules in most cells [2].

References