calcium pump. the mechanism of active transport of calcium (Ca 2+) across a membrane, as of the sarcoplasmic reticulum of muscle cells, against a concentration gradient; the mechanism is driven by hydrolysis of ATP.
A rental agreement differs from a lease agreement in that it is not a long-term contract and usually occurs on a month-to-month basis. This month-to-month lease agreement expires and then renews each month upon agreement of the parties involved.
A lease to purchase agreement is a home rental lease that includes an option for the renter to purchase the home during the term of the lease contract. The contract specifies the purchase price of the home, and in exchange for the purchase option, the renter pays an upfront deposit. The lease portion of the agreement will last one to three years, and the renter can exercise the option to purchase anytime during the lease.