(1) For the purposes set forth in section 1716 of this title and subject to the limitations and restrictions of this subchapter, each of the bodies corporate named in subsection (a)(2) is authorized pursuant to commitments or otherwise, to purchase, service, sell, or otherwise deal in any mortgages which are insured under this chapter or title V of the Housing Act of 1949 [ 42 U.S.C. 1471 et seq.], or which are insured or guaranteed under the Servicemen’s Readjustment Act of 1944 or chapter 37 of title 38; and to purchase, service, sell, or otherwise deal in any loans made or guaranteed under part B of title VI of the Public Health Service Act [ 42 U.S.C. 291j–1 et seq.]; and the corporation is authorized to lend on the security of any such mortgages and to purchase, sell, or otherwise deal in any securities guaranteed by the Association under section 1721(g) of this title : Provided, That (1) the Association may not purchase any mortgage at a price exceeding 100 per centum of the unpaid principal amount thereof at the time of purchase, with adjustments for interest and any comparable items; (2) the Association may not purchase any mortgage, except a mortgage insured under title V of the Housing Act of 1949 [ 42 U.S.C. 1471 et seq.], if it is offered by, or covers property held by, a State, territorial, or municipal instrumentality; and (3) the Association may not purchase any mortgage under section 1720 1 of this title, except a mortgage insured under section 1715k of this title or subchapter VIII or section 1709(k) of this title , or under subchapter IX–A 1 with respect to a new community approved under section 1749cc–1 1 of this title, or insured under section 1715e of this title and covering property located in an urban renewal area, or a mortgage covering property located in Alaska, Guam, or Hawaii, if the original principal obligation thereof exceeds or exceeded $55,000 in the case of property upon which is located a dwelling designed principally for a one-family residence; or $60,000 in the case of a two- or three-family residence; or $68,750 in the case of a four-family residence; or, in the case of a property containing more than four dwelling units, $38,000 per dwelling unit (or such higher amount not in excess of $45,000 per dwelling unit as the Secretary may by regulation specify in any geographical area where the Secretary finds that cost levels so require) for that part of the property attributable to dwelling use. Notwithstanding the provisions of clause (3) of the preceding sentence, the Association may purchase a mortgage under section 1720 1 of this title with an original principal obligation which exceeds the otherwise applicable maximum amount per dwelling unit if the mortgage is insured under section 1713(c)(3) , 1715e(b)(2) , 1715k(d)(3)(B)(iii) , 1715l(d)(3)(ii) , 1715l(d)(4)(ii) , 1715v(c)(2) , 1715y(e)(3) , or 1715z–1 of this title . For the purposes of this subchapter, the terms “mortgages” and “home mortgages” shall be inclusive of any mortgages or other loans insured under any of the provisions of this chapter or title V of the Housing Act of 1949 [ 42 U.S.C. 1471 et seq.].